@Geo ********
You can stay in Thailand doing a border crossing 1 time 2 times that Year. You can only do 2 border runs a Year and then you have to Fly out of the Country and I Love Cambodia and Vietnam and they give us US Citizens a 60 or 90 day Visa. 60 days in 30 Day extension Fly Out for a week and come back to probably 30 days since you didn't return to your home country but if you stay out for 90 days your 6 months start's over again. Until March I found a loophole that allowed me to stay for 7 years until this March when they changed the law's.