The only caution I would give concerning using someone's address (without compensation to that person, ie - "rent"):
If you are audited, and you are living there "free", you take the chance of being determined "itinerate", especially if you have no ties to that site (car registration, voter registration, doctor visits, keeping your stuff there). IF you state you pay them "rent", by law, they should report that income on their income tax.
I have heard about "mail-forwarding" places that travelers use for their "home residence". I question the legality of this; I am to much of a 'fraidy-cat to try it. I have always kept an apartment, and now a house (rent was only $250/month and now the mortgage is <$500/month, so it was very inexpensive). I am not sure how travelers do it with larger rents/mortgages.
Of course, the travel companies don't care if you pay "rent" or not, or keep your stuff there. You usually fill out a questionaire, or sign a statement, that you have a "permanent residence". That way, if you are audited, they are off the hook for providing you with a tax advantage program.