I never have but the idea of using a RV or trailer set up is interesting especially for some big events or prairie dog excursions.
When I a much younger guy, there was an older gentleman who would load and shoot at the range. He was shooting a vintage lever action with some straight wall rifle cartridge. I don't think it was thick as a 45/70. He would literally dip the case in a big can of power, tap the case on the bench to settle the powder, and then seat a bullet. He had both cast and jacketed bullets, and would set up and shoot in 5 shot groups. He was using a Lyman/Ideal style hand loader.
I REALLY wish that I had been SMART enough back then to pay more attention and ask him a few questions...
Back in the hey day of the Varmint Hunter's Association, VHA, the large Jamborees and other associated P-dog shoots, we saw all types of rigs designed for loading and a few for shooting from. Trailers, RV's, vans, truck mounted campers, tents, even a small converted school bus. Some of these were very ingenious, and I most envied the travel trailers that were pulled onto the P-dog towns for living in and shooting from. They had converted windows that open upwards and a fold out shooting bench that allowed the shooter to stay in the trailer and shoot from the shade and comfort of the room.
One gentleman simply had to turn from his indoor bench to use his load station for his 6BR's and 223AI. In those days, it was not uncommon to shoot several hundred rounds a day, so unless one wanted to load an bring a few thousand rounds, which we often did, these guys just reloaded their couple of hundred brass onsite.