Lots of people combine roses with Clematis. It is a time honored combination.

Just be aware that the clematis will likely put on much more top growth the first season or two than will the rose....plan accordingly for supplemental support :-)

I know it wil be beautiful! I hope you post pics of the end result when the time comes. In the meantime, here is a thread from the roses forum of some combos that may inspire you some more. I also have climbing aloha but it's a barefoot And I haven't decided what Clem to use yet. Yours is an excellent choice tho!

Here is a link that might be useful: Roses and clematis inspiration

Oh wow! What a great color choice for shed.

I think those 2 colors will look spectacular with your shed.