Is there a list of acceptable places to live or types of proof of residency that must be supplied at the immigration office? I don't see anywhere in the rules that says person on "retirement" visa must buy or rent appartment long term.

I could choose to live in a differenct city every 3 months - living with friends and sometimes staying in hotels. I could show letter from Thai friends or receipt from a hotel as proof of residency when doing 90 day reporting at different immigration offices in different parts of the country.

Anyone see any problems there...?

It depends upon which immigration office you do your extension at when it comes to proof of residence. Some will accept a rental receipt for proof while other will want a rental agreement and others might not ask for any proof.

Immigration has tightened up the rules for 90 day reporting. You now need to file a change of address at the immigration office where you report if you don't do it where you extension was done. That would create problems because you might need firm proof of residence to change your address.

Having a permanent address to do 90 day reports by mail would solve the reporting problem. You would just need an address where the receipt could be mailed to.

When online reporting is fully functional for everybody that will resolve the 90 day reporting problem also.