Dave, I am having a problem
For Clematis, I put in a search for white and tolerates full sun. Mine did not come up and both characteristic are in the description. Also the data base would not let me add my plant. ( That's the problem, it would not let me add a plant.) I know you are working on this so maybe it will let me later.
GREAT JOB BY-THE-WAY
(Clematis 'Huldine')