Good 12v air compressor

To an extent, "powerful" and "12V" rarely go together for air compressors. Viaiar 12V compressors are generally well-liked and seem to be among the best available. They have several models of varying capability and duty cycle and price.

If you have a generator or a decently sized inverter, a small 120V air compressor may be a practical option and rather easier to find. I carry a Fini AirBoss compressor, ca. $100 or less on sale occasionally from Lowes. I've been quite happy with it so far for typical class C needs (like topping off tires). It would be hard-pressed to do much with, say, an impact wrench or die grinder.

If it clamps direct on the battery only then it is probably a decent compressor.
Anything that draws power from a cigar connector is going to be weak.
I use an MV-50 compressor as needed for at least a decade. Had to replace the hose a couple years ago.

For real power there is Oasis that pulls up to 180 amps ;)

I second the use of a 120v as most 12v leave much to be desired. Have 1 that I tried to use on tires with extensions, would not screw on had to buy an adaptor to make it fit. You should have a generator on the rv so use uit, just make sure you have a heavy extension cord not a cheap imported one so as to allow the unit to run right. Harbor freight is where I got mine $39 on sale. Its the hotdog type single tank 120 PSI I think. Have also used it for light nail gun use out in back yard.

https://www.amazon.com/DEWALT-DCC2560T1-FLEXVOLT-Cordless-Compressor/dp/B0746SBGXS

This is the one I plan to get

these get good reviews Air Compressor

I have an extremeaire from outback extreme. Been mounted under the truck for well over ten years. 100% duty cycle. Several years ago they came out with their magnum. While not as powerful nor nearly as expensive as the oasis mentioned previously it is pretty nice

Extremeoutback.com

Viar makes the best 12v units out there. They're the only ones that strike me as serious pieces of equipmrent.
I've had one for more than 14 years in my truck that powers the exhaust brake and is holding up perfectly to the high temps under the hood.

We've had one from Lowes for a couple of years. It has preformed well, using it to just top off tires and fill air bags etc. It runs on both 12vDC and 120vAC and cost about $30.

Gary