The best I have found so far* is a PVC 5 way side outlet with some short legs for stability and a tall sections based on how high you want to go. I wanted added stability to I made two per lighthouse, and a cross beam on top. Using some old go-pro accessories to attach. *You are right, you want it to be super stable, moving it while its plugged in can seriously damage it.

Could you post photos of them? I'd love to see if it's something I could also build.

I've done just fine with tripods, even fairly cheap ones. The software seems to compensate really well for any potential drift - even if the tripod gets bumped, I often don't need to re-run the room setup to re-calibrate. The most difficult part of the cheaper tripods is that they're often fairly short, so if someone walks between them they lose optical sync. In a pinch I've set the tripods on top of tables and desks, and that's worked well enough.

With a tripod, you don't need to worry. They are perfectly fine for VR, as long as you don't move the tripods while playing.