I have a Viair 200 psi set up (compressor and tank) mounted on the frame rails of my CTD. The only issue I can see is it negates any water crossings. I have it enclosed on two sides so rain and tire spray does not affect it all. It's been going for almost 10 years now! Fire truck air horn, engine exhaust brake, rear air bags and tire filling.
Edit: Oh, and it has a 100% duty cycle at 100 psi!