You most definitely CAN bounce out and back in at the Phu Nam Ron border with burma in kanchanaburi.
You CANNOT stay over night in burma. You get a 'day pass'.
All you do is get to the border, pay 950, stamp out of thailand, get driven across no-manz-land, stamp in and out of burma, get driven back and stamp back into thailand for a new 30 day visa exempt entry.
You can either do it yourself or contact the company SWD Transport (
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They run to that border from Bangkok.
If you go for the 30 day extension it's 1900baht out at the immigration office in the government complex on Chaengwattana Road.