I chose to domicile in Florida and use St Brendan's Isle. They have all the forms you need at their site if you decide to choose Florida. Nice people to talk with also.
People generally look at the states already mentioned because of the lack of a state income tax and also the fact that they treat full-timers favorably as regards Drivers license, vehicle registration, registering to vote, etc. Not to say other states won't work, but you might be blazing your own trail.
Also agree that you don't want a PO Box address. That seems to be a red flag.
My .02
Tim