May I just say, it is delightful to see your outlook shift from powerless to empowered. Wow! Good on ya!

OK, longtime ago, I used to be a theaster costumer. So a few ideas.

I've seen a one=man band guy who has a washboard affixed firmly to his chest (with an accordian harness-type thing) and mounts his harmonica, bicycle horn, kazoo, and other noisemaking objects on top of it, within easy reach of his mouth. I'm not sure if it would be possible to play guitar with such a thing on, though. A Cajun rub-board (frottoir) -- a kind of washboard without the frame that curves over your shoulders like a backless vest -- would be easier to work with, though more of a challenge to mount instruments on. And you'd have to take apart a washboard to make one, which you probably don't want to do.

It seems to me I've seen another OMB who has all his mouth gizmos mounted on a wire "wheel" that spins around vertically in front of his face. It's attached to an axle that (I think) protrudes from his hat. You could, though, accomplish the same thing with a bicycle wheel mounted horizontally on top of, say, a broomstick at whose other end was a big suction cup (toilet plunger?) that you could stick to the trunk, assuming it's a smooth-surface trunk. And if it isn't, you could always glue/tack a sheet of tin to it. Handy for percussion, too, maybe.

The Brittania Coco-Nut Dancers of Bacup (a morris-like group) strap half-coconut shells to various parts of their bodies (knees, hands, upper arms, belt buckles...), which they then clap together for percussive purposes. I think, in your case, knees might work...

Best of luck! I love the limberjack/hi-hat combo idea, by the way.

Cheers,
Claire