The U.S. Postal Service also has a Premium Forwarding Service you might want to check out. They will hold your mail then mail it to you once a week. It can be sent to one set site or else you can call in and have it sent to a different location each week - your choice.
We went to our local Post Office, filled out the form for PFS, and gave them a check to cover the length of time we thought we'd be gone.
Then we called the local Postmaster when we decided where we'd be on a certain date. We found that the best for us was to use General Delivery at a small town's Post Office on any given highway we'd be on in a week or so ..... it calls for a little planning but not too much!
We liked using small towns because there was NO hassle with traffic or parking plus we'd sometimes call ahead and see if the mail is in before actually driving over and the postmaster would actually remember your name when you go in! Love small towns
Good Luck!
Barbara & Ken