What you decide can have implications you may not have thought of.
Many national RV organizations offer mail forwarding services, and they probably work very well. Before you go this route, especially if your mail will be sent to another state, check with your insurance companies. Some consider your mailing address to be your legal residency, which means you could find yourself having to license your vehicles in that state.
We knew from the start, we didn’t want to change our legal residency until we bought a house. We opted to contract with our local UPS store to handle our mail. We got a mailbox and they filled it with our mail. All we had to do to get our mail forwarded was call or email them, and we got it via USPS Priority Mail about three days later. (I found it somewhat ironic that the post office was cheaper than UPS for delivering the mail.)
To cut down on the amount of mail, I requested ebills as much as possible. I also paid our bills via my bank’s bill pay. All of this worked very well, until we bought a house in another state.
We filed change of addresses with the postal service and promptly got a reply they do not forward mail sent to commercial mail receiving agencies, which services like UPS are. Plus, these agencies are only required to forward mail for six months, not the year that the postal service does. To make it even more interesting, while the post office just slaps a yellow sticker on the envelope with your new address, they require the mailing service to pay for new postage for any mail forwarded.