I arrived as visa on arrival from USA for 30 days. Got a 30 day extension at local immigration for 1900bht. Then got the last COVID extension for 30 days in Phuket. I left Thailand and flew to Cambodia for 3 days. When I flew back into Thailand the immigration pulled me over and was not thrilled about my time in Thailand and said I need to get a long term visa or I might have issues in the future. My girlfriend did most of the talking and I told immigration I was planning on leaving in less than 20 days back to USA anyway. I was honest and told him I want to do 6 months in Thailand and 6 months in USA. Then eventually get Thai retirement visa. It also helped that I explained to him my girlfriend had to go back to USA to keep her green card status. Losing that would be a disaster so he knew we were leaving based on the timeframe.