Escapees, but in NV?
Escapees is the only organization that does what they do. But you do not need to have them in the same location as your residence, as long as you have some legal address for service of legal papers. And there is an Escapee RV park in Pharump. Of course, they don't have mail forwarding there.
If all that you seek is a mail forwarding service that you can use as your legal address to be a Nevada resident, there are several that advertise in the RV magazines such as Motorhome and Trailer Life. I know there is one in Henderson.