We use Americas Mailbox in Box Elder, which we made our domicile state. They will do everything except renew your driver's license which you must do. No State Income tax and 4% sales tax. They have several options relative to what mail gets forwarded to you...you make the choice depending on which plan you choose. We've been satisfied customers for eight years.
As with any mail forwarding service, you get charged for the amount of mail sent out...the bigger the package the more they charge in postal fees. We go paperless whenever possible including most magazines..Elks, FMCA, Thousand Trails etc.
That said, as a full timer you also need to look at the other end of the chain. Many campgrounds will no longer accept USPS mail and/or they charge a fee for doing so. We go on line to the USPS site and have our mail forwarded to us in our name, C/O General Delivery. Not every post office accepts GD so you have to check to make sure the one nearest you will do so....best of luck...Dennis