I keep my compressor in the rear cubby. Too much salt on the winter roads for me to feel ok about an external mount. Already have to combat rust elsewhere on the truck regularly so I put it inside and havent had any issues. Also is in a great position for inflating camp gear like our air mattress and river rafts. I run a 5 way manifold with gauge that can simultaneously inflates all 4 tires. Its a bit of hose but all fits well in my recovery gear tote. Tire specific lengths with quick disconnects allows me to sit in the warm, dry truck and monitor PSI when its cold and wet out which is most of the time here.