I did a Muay Thai visa to stay previously (similar situation, thai partner, no recognition of gay relationships, etc). Had to train Muay Thai 90 minutes a day, 4 or 5 days a week.
Alternatively you can do education visas in Thai language, Thai massage, self defense, Thai cooking, scuba diving - you just need to find a school certified by the ministry of education to offer the visa for their teaching, but in Bangkok I would imagine most education options would be available somewhere.
Most education visas only require commitment of an hour or 2 a day, 4ish days a week.
Does anyone know who I would contact if I live in Cambodia (and have proof of residency), but am currently visiting Thailand (British citizen with Thai partner - both live in Cambodia, have had our flights cancelled).
Our home and all our stuff is in Cambodia, we really need to find a way to get back in - no idea which authority to speak to about it.