Idk about retirement visa. But we are a family of 6 and our amount is 2k usd/month with 2 ED visa. I think you’ll be alright. It’s subject to change the way you live and spend your money. We don’t have a vehicle and don’t drink and only go to the doctor office if needed.
my husband and I are on ed visa through CMU but that’s because we are here as missionaries and have to learn the language. But if you guys don’t have to learn the language I’d go with muai thai.
Apply for a ED visa outside of Thailand. And remember to apply for each of your kids online Thai consulate. I went wrong there. My kids ended up coming to Thailand on a 30 day exempt and now they are over staying. There is no penalty for kids under 15 to over stay in Thailand.