Feedback at moderate to high gain is the reason solid and semihollow guitars were invented in the 50s. Hollowbody and real loud just don't mix unless you're a long way from your amp or you take steps to make the guitar act a good bit less like a hollowbody, and then why would you need a hollowbody?
Gibson invented semihollows to reintroduce some of the resonance (amplified) of a hollow guitar, but the reason hollowbodies are relatively loud unamplified is that the top is free to vibrate. It's the vibration of the top, not the strings, that makes the volume. That's also, mostly, why they feed back: sympathetic vibration of the top in all its resonant frequencies. So any kind of contraption that hinders the top's vibration is going to 1) reduce feedback, and 2) kill unamplified tone. Sadly you can't have it both ways.
By the way, it's not only the top's vibration that leads to feedback; I have a custom-made semihollow where the center block does not extend all the way to the back. The back's freedom to resonate gives the guitar a super tone, but it's way more prone to feedback than my ES-335 -- and way less so than my hollow Casino.
Good luck...
Chandler