Upright "tree" for shady corner - ideas? input?

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There's a section of my back yard where I'm planning on taking out an old Ostrich Fern (Matteuccia struthiopteris) and replacing it with something with a bit of height. The area gets a few hours of very early sun, generally being fully shaded by 9:30 in the morning. I suppose there's some filtered sun through the afternoon through the fence and it's fairly bright there but I'd still call it very shady. It's also a very sheltered spot that gets reliable, long lasting snow cover.

I wouldn't mind some good height up to 6 feet or so but it really needs to be less than 3' wide - at least at the base. It could get wider higher up but still no more than... I'm not sure here - 5 feet wide?

Neighbouring plants include a Maidenhair Fern (Adiantum pedatum) which is staying (Ultimately I'd like it be able to give this a little more room by removing the Ostrich Fern), an Actaea simplex 'Hillside Black Beauty' which is either staying exactly where it is or is switching places with the new plant (putting it directly into the corner and possibly allowing for more width from the new plant), and a pink Turtlehead (Chelone obliqua) which is definitely at least getting divided, may switch places with a white Turtlehead (Chelone glabra) which seems to be a little smaller and slower growing.



Adiantum pedatum - I wish could still see this as well as i could when this picture was taken!

So far I've considered a few things, such as...

Evergreens. I like that there would be a little bit more interest over the winter, but the plants that would work are not thrilling. Most would involve some shaping (being distinct from pruning here in that it will not have a natural shape) to work.

Boxwoods (not likely, I have another maybe 10 feet away and frankly they're boring. 'Green Mountain' would give the height but would definitely need some shaping to keep it in line and attractive)

Yews (maybe - Taxus baccata 'Fastigiata' is not reliably (or even borderline) hardy though it seems it would be perfect. Hicks or Hills Yews may work... with more pruning for both height and width but I'm less thrilled about the idea)

Standard Euonymus - Would give height, almost no space taken up at the base of the plant, could definitely work.



Purple Rhododendron - Colour is similar to 'Lee's Dark Purple'
(Photo by Sebastian Wallroth used under CC license from here.)

Shrubs pruned into small "trees":

Rhododendron Lee's Dark Purple is absolutely gorgeous and my preferred choice. I'm a little hesitant because I worry about how well it will take to pruning. I'd like to grow it as a small multi-stemmed tree with bare lower branches. Most people here have problems keeping the large leaved Rhodos alive, never mind worrying about having to prune them to keep them smaller. Spring flowering would be very welcome, evergreen is a bonus and I love the colour, I'm just not sure how practical this would be.

Small Trees pruned into even smaller trees:

Redbud - Either straight Cercis canadensis (can easily get smaller specimens relatively cheap) or 'Silver Cloud' (not likely but a prefered option). Would require some staking of young branched to give it a narrower form but after that would not be unmanageable (I think). Third choice, 'Silver Cloud' could make that a higher option on this list. Spring flowers are something badly missing in my garden and the added interest from the leaves would make that a very tempting choice.

Fagus sylvatica 'Dawyck Green/Gold' is definitely narrow enough at the size I'm looking at. These respond well to pruning but in the heavier shade of my garden would likely be slower growing - 'Dawyck Gold' would also not be as "Gold" but I think I'd actually prefer that. Bright green is good enough. This is likely my second choice - it would go in the corner and my Actaea simplex 'Hillside Black Beauty' would move to where the Ostrich Fern used to be. The bright green leaves would be a very attractive backdrop to the black ferny leaves of the Bugbane.

Serviceberry (Amelanchier canadensis) I don't know how well these take heavy pruning but it's a nice tree. Trying to prune to maintain a small size while still getting both flowers and tasty fruit would be a fun challenge. I think fruit may ultimately have to be sacrificed to get a small enough flowering tree.

So... I'm leaning towards the Rhodo, pruned to keep lower stems bare; the Beech, pruned to maintain a narrow form in case any branches start growing outward, eventually to control height as well; or a Redbud, shaped from a young age into a narrowly upright vase shape, later pruned hard each spring to keep it small.

If you can think of a reason why I should avoid any of the above options, or maybe I've missed something that might be a good option? Are any of the plants I've mentioned not really practical to try and maintain at a relatively small size?