[FrankR]

Having owned a GMC front wheel drive RV for 12 years should qualify some info.
Just a little basic info. Never connect any load with out some protection, as a fuse. The new car fuses are called ato and many styles of fuse holders are available. Pick a holder so fuses are everywhere. My guess[swag] for a fuse size would be 30 amps. In an other life, with the GMC, I installed a mechanical air guage in sight of the drivers seat with a switch that controlled a relay at the compressor. Additionally, I fabricated a air tank from some 4 inch schedule 40 PVC pipe, about 24 inches long with glue on end caps. The bursting pressure for that size PVC is about 480 psi. This PVC can be threaded for a 1/4 pipe fitting. The line to the dash guage was 1/8 inch nylon. At the air bags, there was a small 3/8th ball valve and a shrader fitting to be able to add air from any source, as a gas station, etc..
Some guys, got and connected a small 120vac compressor that could be powered by a shore line or their inverter. GMC 12 volt compressors were usually located near the radiator.