I'm going to reply in part to your question.
I grow the regular ninebark in various shades of green and a 'diablo'
Both are fast growers. I would suggest you prune the 'coppertina' often thoughout the growing season to keep it as a background plant only especially if in part shade.
The Ninebark grows in any type soil. Leaves are sometimes smaller if pruned to the ground occassionally as I do on some & on others are larger for some reason. I have a row of six ninebark beside a driveway and the branches are reaching over the driveway now.
Hopefully the 'Coppertina' will not sprout gigantic "arms" as does the 'Diablo' after being cut back to ground in April!
If I were lucky enough to keep a Rose of Sharon growing in this zone I would probably, in your situation, try the Hydrangea & hope for good flowering in that site in the spring followed by the beautiful blooms of Rose of Sharon in August!
Sharon

I spoke with a friend of mine from the RBG and she told me that the coppertina ninebark does not like acidic soil nor would it hold its beautiful color without sun ... I agree with Sharon ..