The adhesives and wood supports will work well in places I don't mind a large/long support with plenty of area to be glued. Good chance I'll use something like that for the AC unit in the closet, so thanks for the info and links.
But, there are plenty of places I'd like to put a small, unobtrusive bolt into the wall. For shelves I'd like to remove without leaving large supports, to put a small fitting/fixture, like a shower curtain holder etc. For those things I just want a small attach point. Ideally just a small hole in the fur when nothing's in there. But that could hold a decent load.
Here's my first experiment. I'm thinking I can make a small 1"ish cut in the fur, spread it open and hold it open with a 2" slice of PVC pipe or something like that, tape plastic sheet on the outside of the pipe to keep the resin off the fur, insert my little device and resin it in place. Pull the fur back as much as possible, perhaps find a small, round, tan plastic flat piece, drill a hole in the center and use that around the bolt hole to cover the disturbed fur to give a clean look.
I used the fiberglass cloth I have from an impulse buy and used a few dabs of "super" glue to quickly wrap a layer around my wooden "puck" with the T-nut inserted into it. Then took two layers of cloth on either side, a few more dabs of glue around the edge of the puck to hold the two pieces on the puck until resin is applied.
I suspect my first attempt will be a mess. But that's why I'll be putting a few of these in under my dinette seats where ugly won't matter.