Japanese (and other Asian) maples are by nature understory trees and are accustomed to a part shade location. "Ideally", a situation that provided morning sun and afternoon shade is a preferred location, avoiding the more intense and hotter late afternoon sun. However, most red leafed maples can tolerate a great deal of sun without issues, provided all other growing requirements are met. Given the two locations outlined above and the size of the tree now, I'd not be too inclined to move it - it will be far less stressful and better for long term growth to leave in place. A JM with a 2-2.5" diameter trunk is a good sized tree and will not transplant easily. And you certainly do not want to comtemplate doing so now - if you must move, wait until dormancy.

IME any of the H. paniculatas would work, or as others have suggested, a mix of them is a really great idea. Here they have thrived in full sun without irrigation, unlike the H. macrophyllas and H. arborescens, which like afternoon shade and periodic water. I would visit nurseries and look at the flowers of various types of H paniculata since the panicle's shape, density, and color varies a lot. I have Quickfire and Pinky Winky and prefer QF: the longer bloom time, the looser and more rounded panicles, and the color, which starts with white flowers around July 7-11, slowly shifts through a pale pinkish, and ends with a glowing cerise that lasts until hard frost. Pinky Winky starts later, has very dense pointed panicles, and still has a lot of white at this time of year. I am not overly fond of Limelight's fall color fade, though the summer is stunning, so having it as part of a mix would be a way to emphasize the positives of each while letting the less attractive aspects fade into the background, letting the ones that are at their best capture attention. My H. paniculatas leaf out with the majority of the other deciduous woody plants in my area, not early or late, so you will have time in the spring when you want to be outdoors but they don't provide as much privacy. My computer is in for repair, so I don't have normal access to photos, but I will look for some and add to a followup.

Below is the info. that Floweraremusic (zone 5) in Washington gave on her 2020 winter-survival. She has alkaline clay with rocks at bottom like mine & less snow in winter: "My hardiest roses are the Canadians. John Davis, John Cabot, Wm. Baffin, Morden Sunrise, Morden Blush and Morden Centennial, Victorian Memory aka Isabelle Skinner, also a Canadian rose. All these only have tiny bit of tip damage and bloom a lot with no special care. Also, my Hybrid Perpetuals only have tip damage after winter. Magna Charta, Mrs. John Laing, Black Prince and Marchesa Buccella. The only negative is they don’t have long enough cutting stems. All my Austins are very hardy. The one I just can not grow is Jude. Leonardo da Vinci is super hardy and always healthy. Quietness comes through winter very well. Even Rouge Royale survives beautifully. Cinderella Fairy Tale is very hardy. Gruss an Aachen also. Ballerina and Marjorie Fair are both hardy. Poseidon, Princess Charlene de Monaco and Crazy Love didn’t do as well as I’d hoped. The surprise losses this year are Quicksilver, and Dames de Chenonceau who is left with only 1 cane. Versigny is also reduced down to almost nothing. This was a mild winter with very little snow. " Floweraremusic (zone 5). From StrawChicago (zone 5a with hard black-gumbo alkaline clay & less snow but with freezing rain in winter). Versigny didn't survive winter either. So I lost Versigny TWICE. Besides Versigny, other wimpy own-root roses that don't survive winter well: Paul Neyron, Anna's Promise, Pink Peace (own-root died 1st winter, but grafted-Pink Peace survives many winter), Elantyne, Jude the Obscure, Young Lycidas (bought as grafted-on-Dr.Huey, now with only one cane), Mary Daly, and many floribundas don't survive my zone 5a: Pink Chiffon, Sheila's perfume, King Arthur, Deep Purple, Shocking blue, Honey Bouquet (survived 1 winter). Polka Climber (survived 1 winter), Cloutilde Soupert (died twice on me). Sutter's Gold didn't survive winter, same with many fragrant mini-roses from Burlington nursery. Below are my hardy OWN-ROOT roses in my zone 5a alkaline clay, only Double Delight, Young Lycidas and Lavender Crush are grafted-on-Dr.Huey. Bold-faced are the very vigorous ones: Own-roots with 3 feet of green canes: Carding Mill (since 2012), Princess Charlene of Monaco, Duchess de Rohan, Crown Princess Magareta (since 2012), Zepherine Drouhin, Lady of Shalott, James Galway, Lavender Crush, Queen of Sweden (gave away but very hardy), Poseidon (right below the rain-spout, dug down to 2.5 feet), Scepter'd Isle (very big & hardy own-root but gave that away with its lousy scent). Own-roots with 2 feet of green canes: La Reine (many winters), Blue Mist (since 2012), Prairie Harvest (since 2014), Mary Magdalene (since 2011), Evelyn (since 2012), Radio Times (since 2011), Pat Austin (since 2011), Christopher Marlowe (since 2011), Golden Celebration (since 2011), Lilian Austin (gave away but very hardy), the Squire, the Dark Lady, Wise Portia survived 4 winters but died in poor drainage clay, Dee-lish (since 2015), Twilight Zone (since 2016), William Shakespeare. 2000 (since 2011), Comte de Chambord (since 2012), Princess Anne, Sweet Mademoiselles, Aloha climber, Orchid Romance, Bohemian Rhapsody, Marie Pavie, Lagerfeld (since 2017), Frederic Mistral survived 2 winters but died when I didn't winter-protect with leaves, Sonia Rykiel (survived 3 winters) but died in freezing rain winter, same with 1/4 of the street-trees in my neighborhood, Excellenz von Shubert (since 2013), Own-roots with less than 1 foot of green canes: Gina's rose, Tchaikosky (since 2015), Cornelia (since 2018), Bolero (few winters), Peter Mayle, Sharifa Asma, Neil Diamond, Amber Queen, A Shopshire Lad, Strike it Rich, Old Port (since 2012), Veteran's Honor (many winters), Double Delight (grafted on Dr.Huey), Savannah, Tess of d'Uberville, Gene Boerner (since 2014), thornless Yves Seedling (since 2013), Stephen big Purple (since 2012), Louise Este, Mirandy, Crimson Glory, Liv Tyler survived 1 winter but needs winter-protection, Rouge Royal (bought last year with no winter-protection). Annie L. McDowell (survived 2 winters but needs a wet-spot since it's almost thornless), Nahema (survived 1 winter then died during freezing-rain winter), same with Eyes-for-you (drought-tolerant and doesn't like freezing wet winter), Souvenir du President Lincoln, Madame Issac Pererie and Madame Earnest Calvat, Firefighter (survived 2 winters) but died since it's next to tree. Bayes Blueberry (survived many winters but I gave away), Charles Darwin (gave away since it fades badly), Arthur Bell (since 2012 & killed it since I don't like the flowers). StrawChicago.

First off, I'd go with something EVERGREEN. That way you'd have screening in winter. Then, I'd go with something that makes a small tree and remains more or less vertical in form without getting too wide -- but could be easily sheared if needed. Are you able to water these and maintain them? If it were me, I'd consider a holly - vertical grower and a dense grower, but try to get a less spiny one, as there are many hardy to your region... like Yaupon, Ilex cassine, 'East Palatka', 'Spartan', 'Scepter', 'Virginia' (hard to find), Ilex integra, Ilex buergeri, Ilex chinensis, Ilex rotunda, x wandoensis, or Ilex 'Eagleson'. (many of these may be impossible to locate in your region). Spinier (so, harder to work around), but equally attractive and functional hollies could include 'Savannah', 'Liberty', 'Homefire', 'Fosters', 'Christmas Jewel', 'Mary Nell', 'Oakleaf', 'Oakland', Ilex latifolia, 'Lassie'. Other plants to consider might be Magnolia virginiana (australis -- evergreen), Ternstroemia gymnanthera (Cleyera), Podocarpus, Viburnum awabuki 'Chindo' (needs reliable moisture), Viburnum 'Pragense' (needs regular pruning to tighten up), Prunus caroliniana 'Bright n Tight', and Osmanthus fragrans (fantastic fragrance), Photinia serrulata (Green Giant), Osmanthus x fortunei (spiny), Distylium racemosum, Laurus nobilis (Bay), Japanese Blueberry Tree (Elaeocarpus decipens), Loquat, one of the smaller Mag. grandifloras such as 'Teddy Bear' or 'Baby Grand', Wax myrtle, Red Bay or Swamp Bay, Quercus phillyreoides, and oh so many other possibilities! You could even mix in some Trachycarpus palms or Sabal palmetto into the lineup. I'd be tempted to put in, say three Trachycarpus (Windmill palms) equally spaced out at first. Then fill in between them with hollies, osmanthus, or some other broad-leaf evergreen. I don't know if you are near a large metropolitan area with good nurseries and diverse plant availability or must rely upon Home Depot or Lowes.