Does that come in tree form? Need something taller than 5'

'Hicksii' AKA "Hick's Yew" is a very popular upright cultivar. There are other columnar cultivars.

Pointed tops like you have drawn will appear to be stabbing up into the crowns of the maples and produce a visual tension. Also notice how only the lower portions of pyramidal trees such as the ones you have added have enough width to provide much screening - it would be much better to use forking kinds that eventually produce broad, flattish tops. Such as the many old tree-sized hybrid yews seen in my area tend to have - I would expect any cultivar of this cross chosen to grow multiple increments of 5 ft. tall over time. Unless it was a quite low, ground covering type.

Any of the existing trees that can be removed will greatly increase your ability to produce an evergreen screen of some vigor and density. The Norway maples for instance, which are a nuisance species in North American woodlands anyway.

Taking these out would also assist the native tree species that are growing near them.

Finally, as with all such situations where there is a desire to visually eliminate something that is bothersome right now it may be necessary to erect an architectural solution such as a fence in order to get anything approaching the effect being visualized. A visualization that includes that the effect happen within a short time - a planting of yews for instance in that very tough situation might grow inches per year. And in such heavy shade probably nothing planted is ever going to block headlights completely - perhaps not even if the entire 20 ft. depth is filled with shrubs. Because just about anything placed beneath the existing continuous canopy of trees is going to produce a markedly thinner growth than it would in a well illuminated position, no matter how shade tolerant it is otherwise.

Good point on shape. We were originally going to use Blue Spruce but were told it wouldn't do well in that degree of shade.

It is a protected ravine so we can't remove any of the trees.

We'll have a look at the Yew's you mentioned and see what sort of mix we can come up with. Japanese Maple would do well further forward so it receives 6 hrs of direct sunlight. See if that works with our plans for garden in that corner.

To Embothrium's point I've struggled with this type of situation as well. There are certainly options for the shaded location but the shape is tough to get right visually among the tree crowns. Its almost as if a Yew or Hemlock is the only choice as everything else is columnar or pyramidal.

I wish there was a broad spreading, flat top cultivar of Picea glauca.

Hemlock is a conical conifer also. And is being eliminated by hemlock woolly adelgid.

Japanese maple is deciduous and drainage sensitive, prone to blight problems (when horticultural selections are chosen). (Yews also must have good drainage).

Look at similar situations in the vicinity and see if anything is present that seems to be producing the desired effect.

It's iffy that far North, but I usually like American Holly for that role. Somewhat shade tolerant...pyramidal, but not as pyramidal as a blue spruce, pretty.

I found this statement interesting: "It is a protected ravine so we can't remove any of the trees."

Is it protect by a government, HOA, City,County State,etc?

If it is protected how can you introduce a new species into the environment?

Just curious, as I never have run into this situation.

Plant and/or build on your lot instead of over where the unwanted element starts to become visible and you can control what is done. And it is more efficient as the farther away something is the smaller it is visually. So when a screening attempt is made way over where the disliked occurrence starts to become visible the screening used is much less effective that it would be if it was in close to where you are looking from.

Our list to consider:

Wheeping False Cypress

Mountain Laurel

Sky Pencil Hollies

Japanese Yew

Hicks Yew

Hemlock