We have used Dakota post (an FMCA member) a few times, with mixed results.
The service we used was their short term/90 days or less. We also put a temporary change of address in with the PO at home, to the address and PO Box assigned to us by Dakota Post. Since their are two of us, with different last names, we have to put in two change of addresses. The last two times, the Post Office..not Dakota Post, failed to put the box # at Dakota Post into their system for Becky only. Mine was fine. We kept copies of our submissions and they were exactly the same except for the name. Consequently, Becky's mail was over a month old when she finally received it because DP had no idea who she was (the contract was in my name) without a box # on the mail.
DP always sent our mail Priority Mail (an additional fee) however, sometimes it was late, and there was a time we had to stay at a campground an extra day because we were waiting for mail that should have arrived earlier. It created some problems with our itinerary.
Another potential problem is if you lose, or a credit card is compromised in some way. The bank will only send the new card to your home address, which will get forwarded to the mail forwarding service..or..not at all as some banks have an agreement with the PO that they cannot be forwarded.
When we were in Gillette a few years ago we had a month's worth of mail sent to the Fairgrounds, knowing we would be there 10 days, including the Beaver pre-FMCA rally. The forwarder sent it. But to the fairgrounds address. When the mail didn't arrive in a timely manner, I did some inquiries. According to the PO tracking it was delivered on the day we arrived. No one at FMCA had our mail. Finally I went to the Gillette PO and talked to the carrier who delivers there. He said he put my mail in the fairground's mail box out in front of the main office. No one there had it either. I finally found the mail, two days later, in a security office up on the second floor of the main exhibition hall. The mail forwarder just put my name and the address of the fairgrounds on the package/envelope. There was no mention of c/o FMCA as instructed.
Just some things to be aware of when choosing to do short term mail forwarding.