I'm surprised no one has mentioned state residency in conjunction with a mail forwarding/handling service.
For many years now I've been using Americas Mailbox, in South Dakota as my mail forwarding service. Unfortunately they only do forwarding, not document scanning The price is also not as competitive as others mentioned (such as Traveling Mailbox).
But the ability to be a South Dakota resident and have a drivers license is the primary reason I've stuck with them. My home state was requiring me to pay state taxes despite the fact I hadn't lived there in over 6 years. They wanted me to prove residency elsewhere, which, being a digital nomad, I couldn't.
In the end South Dakota is friendly to full-time travelers (most of which are elderly, retired, domestic full-time RVers), and I only need to return once every 5 years to renew my drivers license.