I like my Firestone setup with manual independent controls and gauge in the cab. Air compressor works off a pressure switch with an attached small tank 1 gallon (?). Tank keeps itself at 80 psi. Without the small tank, the typical bleed of air lines and reduced pressure due to temp changes would likely bump the compressor frequently.
It's nice just to lift the valves in the cab to get air in the bags or to dump air. If I need to add air to bikes I drag out a coiled up air line with fittings already attached. I keep a spare mini compressor in the Rv, just in case - I could back feed into the tank
My on board compressor is small and not recommended to fill truck tires, but has done the job, just takes longer than the duty rating.