I never liked the idea of running my compressors under the bed. We have too many rocks and other debris on our roads to risk damaging the equipment. In order to keep all of the parts clean (because also display them at shows)....I, like others put them in the bed. IIt's all up to the end user though.
Be sure that you use dot rated air lines too...at minimum 3/8" dia. Trust me, you don't want a line burst when driv7ng down the road.......been there and done that. It's not fun. I alo recommend having some extra line fittings, extra hose and a schrader valve handy as a just in case scenario. If you lose a compressor at least youmhave an extra way to air up the system. Extra airline fittings can come in handy if you have to splice in and repair a broken line. Its better to be prepared and never use the spares, then sitting on the side of the road waiting for help.