Check the Home Depot stores. I bought a real nice compressor there, but mine has a eight gallon tank which holds up to 125lbs. I keep 100lbs on the front tires and 90lbs on the duel tires on the rear. If you put too much air you take away a lot of the smoothness on the ride. My coach weights 30K diesel pusher, I am not sure what yours weighs, but it seems like the air pressure is a bit high on the rear.
But Home Depot has different configurations on compressors. Some small enough to handle what you want.
I used to have a small compressor that I had bought at WalMart with no reservoir and it claimed it could pump up to 150lbs. They lied! It could barely fill up a car tire much less a huge 22.5 tire.