So, for 50 weeks out of the year you use the vehicle to move furniture, and 2 weeks out of the year (in the cold of winter) you will use the vehicle to camp out of? Do I have that correct or are you talking about 2 different vehicles? What kind of vehicle are you camping out of? Off grid, semi...
Following the initial idea by OP take the bottle to a home center and see if you can adapt the spigot area to garden hose thread, then put a garden hose female quick disconnect fitting w/ auto shut off on bottle, then modify a piece of garden hose with the male quick disconnect fitting on the...
Elmo's New Toy Hauler Build by Elmo_4_vt shows a build using a trailer he acquired from trailershowroom.com check it out (both build & site) I don't know if that is what you are looking for.
Truck bed is an 80-86 Ford, looks like a 6' bed, but a pair of lights from 87-91 or 92-96 F-150, 250 or 350 should also fit.
If you want to run a single tube from front to rear to use as the trailer coupler mount in front and as a hitch receiver in the rear it should have a 2" X 2" inside...