Japanese willow, Salix integra, is really a shrub, of which the dappled or variegated cultivar 'Hakuro Nishiki' is the most popular form. If you have a tree-like plant, then it has been grafted on another willow rootstock. Any shoots coming from the base or along the trunk are from the rootstock and need to be removed. They will overtake and choke out the grafted portion in time if allowed to grow unchecked. You can and should remove them whenever you see them emerging. Otherwise, the shrubby form (or the top portion of your grafted form) can be pruned to size in late winter/early spring as it begins to push buds.

You're correct - pollarding/high coppicing is a LOT different from normal pruning practices :-) Generally, pollarding is cutting back all the branches to the central or main trunk, which is why it's a good idea to start this training practice while the plant is still quite young. The grafted feature of your willow encourages this. Some of the larger branches can be left and are then cut back severely and left as stubs (in total opposition to regular recommended pruning cuts). Look again at some of the online photos and how-to's....most do not show just a willy-nilly hacking back but a pretty complete removal, typically on an annual basis. It's a pretty radical technique and maybe a bit daunting to the fainthearted but it's been around for eons and is usually quite successful.

well - its not that you can't. Its what may occur later on. You may have seen a number of ficus plants being braided like this and that's actually in the nature of ficus which are in the wild, considered parasite trees (they grow up trees and eventually strangle them). its fine for those tropical plants. With dappled willows though it could be a different story. You would notice in tree shaping how branches growing too close to another are separated and sometimes one will be cut out. This is because those tiny gaps in between is an area vulnerable to insects, ice, disease. I'm not too sure about the strangling it to death part of it. Just beneath the outer bark layer, the is the layer that's responsible for carrying up nutrients - basically plant veins. So if that gets strangled then some of the branches can be affected by that process. -- that is if those bark areas are compromised.

My concern is that the willows may become too much work to manage. -->>> i suppose it depends inf you are 20 1ish ... or 60ish .... willow is aggressive.. and will need one or two trimmings per year ... its not a plant i would want to have to prune at my age .. how about a pic of your spot.. and ask for suggestions other than those in the box you are already in ... i dont understand why you need a 10 foot hedge???? look here.. look for single non pruned plants.. frankly.. one will fit in your 8 by 10 spot .. do not fixate on the pix of many plants on an estate with a gang of 20 gardeners to prune them .. https://duckduckgo.com/?t=ffcm&q=Dappled+Willow&iax=images&ia=images ken