Yes, I've previously read that and also:
https://codimd.laas.fr/s/NMc3qt5PQ
I don't see anything in those that conflicts with what I've done.
Unfortunately there's been very little written on this subject from real practical experience with the latest OBSD. For example Solène writes:
This guide should work from OpenBSD 6.9. (My use of bold).
Hence I'm appealing to others to give it a whirl! I've also tried testing with/without rdomain setups with a free 7-day WireGuard setup with vpnjantit:
(
https://www.vpnjantit.com/free-wireguard)
with similar issues. It works without rdomains but not with.