I'm tempted by the RV places and their scans, but I think I am going to go with the small business mailbox shop down the street from my S&B.
I had a nightmare situation last winter with a very valuable package going back and forth across the Atlantic 4 times, going off tracking for weeks at a time and reappearing in another country, etc. This made me aware that forwarding does not always work well -- so I want my mail to be somewhere I can physically get to it or send a friend, not in another part of the US :).
IME the USPS forwarding system is a disaster. There is no way they could cope with forwarding my mail to another state temporarily, and then delivering to my S&B again in the summer. Part of the problem is that my S&B is on the route they use to train newbies :(.