We've used
MyRVMail for four years now and they've been great.
It will enable you to have a street address so you can get a driver's license, register your vehicles, register to vote, etceteras. They were very helpful in getting all that done.
Also, their web interface will show you what mail has arrived and you can chose if/when to have it sent or they will shred it at your request.
GoodSam members get a discount.