I hope you're able to come up with something for your situation.
I'm trying to come up with something to shade some hydrangeas and brugmansias from 4-5 hours of late afternoon baking sun --we lost a huge tree to the west of them last June in a really bad storm.
They barely made it through last summer with the heat and drought.. Its not looking good already.
I can see the caster bean trees I planted aren't going to get big enough soon enough to shade them. There's not enough sun for them to grow big and fast as they're shaded most of the day and the other tree roots just suck all the water up.
So now I'm thinking about erecting a cheap temporary trellis and growing a fast growing vine that can take mostly shade and a blast of 4 hours of really hot sun. Something like black eye'd susan vine might work there, or some sweet potato vine maybe.
We'll replace that tree this fall but it will be quite a few years before it will be able to shade the area again.
If that doesn't work I may have to rescue/move those plants in the dead of summer and pot them up until I can find more shade for them.
I thought about some elephant ears planted close by, but I can't dig a big enough hole to plant them! Too many huge tree roots right where I need to put them.