I am a U.S. citizen, I will be marrying my Thai fiance sometime this year. Which should I do, retirement or marriage visa?

So I’m currently 34 and a US Citizen. It’s my goal to live in Thailand full time by the time I am 40. What are the best options to make this happen with the least amount of money necessary?

Does anyone have any knowledge or experience around what is required to obtain dual citizenship? More specifically, has anyone ever had to acquire a birth certificate in Thailand.

My situation: I was born in 1973 on a US Army base in Bangkok. I had a US birth certificate but also remember seeing a Thai birth certificate at one point. Both of my parents have passed away and I am looking at the possibility of moving to Thailand to try and connect with my heritage. Anyone else the child of someone from the military? My mother was a Thai native and my father was in the US Army until they brought me to the US in 1974.

Is there any moments at one stage of his life when married to a thai lady Farang living in Thailand don't have to do any 90 days report or any check-in or i don't know what else ...

and then he can just live peacefully on a farm away from city and away from any papers or it is just a utopia?