I've been asking this in some of the other forums, with mixed answers. This place seems like it might have more actual experience:

Does anybody have much experience growing grapes up trees? I have a large maple tree. I am considering running a muscadine (so I don't have to spray) vine up it. I would not maintain it, beyond perhaps some very occasional pruning. Any fruit I would get would be pure bonus, coming from an area that would otherwise produce none.

I know everyone recommends sun for grapes, but in the wild they grow up trees, so I assume that's just for max production. If I'm ok with low yield, is there another reason I should disregard this plan? My goal here is not high production, it is using space that would otherwise not produce any fruit at all.

Here is a link that might be useful: Cross-posted to Fruit & Orchards