Ride Rite Replacement Compressor

Viair is a known supplier and likely good quality. They have a wide range of onboard air systems. (Disclaimer - I don't have an onboard compressor, not an interest in Viair.) You could get by with a tiny compressor if you put in a storage tank to store high pressure air. As long as you didn't try to fill the air bags frequently (like every 10 minutes - not a real need to do that), a little compressor would do just fine. It would just run a bit longer to recharge the tank.

You should be able to replace just the compressor and wire/plumb it in just like the original.

That's either a little bitty compressor or a really BIG knife.