Bolt in valve stems are reliable and are essentially the same thing you're needing to do- a threaded fastener through the rim. So you could steal washers from there. The big difference is that, with a rim lock stud, the threads are on the exterior and the air would want to chase the threads out. Valve stems are easy since the solid part of the fastener is outside.
If you ran a solid aluminum rim lock ( or some other design that would accept threads) with the stud removed, tap the hole and use a bolt rather than a stud...it gets you halfway there. The seal you lack then, thinking of valve stems, is the inner washer. There's no way to compress an inner washer/seal on the inside, so you're stuck relying on on outer seal only.
Plus, rims are almost always crowned in this area, so you're behind the 8 ball right off the bat, not having a flat surface to work with.
🤔
What about an inner tube? 😁