W.E.BGood, I bought these 2nd hand off the truck forum. There's no return. I also bought the compressor 2nd hand also. I'm pretty well committed. :)
But I wanted a separate compressor and tank anyway. I want air on board so I can air my own tires up & down as necessary and just to have in general. It won't be designed to run anything more than that, but it'd be nice to have and I bought the stuff almost half off new. Couldn't turn that down.
As for plumbing, I'm going all electrical and relays. It's a bit more expensive, but then I can leave all the air connections outside.