I’ve been coming to Thailand for over 20 years you used to get 30 visa exempt and a 15 day stamp if you did a border run but it’s irrelevant you need to follow the rules/laws as they are now not as they were 🙏
I’ll say again you can stay as long as you like as long as you get the correct visa, what’s hard to understand, the boarder runs have always been a grey area now there just clamping down
the O-visa is a 90day non immigration visa it’s the one I’m on at the moment I plan on extending based on marriage in the new year, hope you get sorted 🙏👍