You say 'about to go full time'. Does that mean you just sold a house ? Or are now in an apartment ? Is your PO box in the same city, state ?
What do you mean by 'current state of residence ? Is it the same as one of the above ?
What address is on your Driver's license right now ? Your vehicle registration ? Is it the same as one of the above ?
I fulltime and am 'domiciled' in Florida. That address is on everything - driver's license, IRS, Banking, vehicle registration, etc.
I recommend that you talk with the Escapees folks in Texas, or my mail service - St Brendan's Isle, in Green Cove Springs. Ask questions.
I have no direct experience with just having a PO box for an address, but there has been much discussion of that here. I know some folks say it does not work very well, but others say the opposite.