Okay, this is off the wall. If youll please allow me to present this, I promise this is as far out there( off the wall) as I will get.
Okay, heres what done;
I've "Live coupled "my Mahogany Strat headstock to my solid oak cabinet Pro Reverb style tube amp.
What this basically means is you apply pressure to the headstock at a point on the amp cabinet where its most likely to resonate at volume.
Man- theres some serious tone to be had doing this. Not that Im the only one to do trhis , cause of course many players have rubbed and slammed their guitars up against their cabinsets.
I'm just noteing that it can be done sans any theatrics and to measured effect to reproduce a really organic feedback.
It does involve some judicious volume and dilaing in your amp so that its recpetive to, or right on the verge of feedback.