Viair 400P EF A compressor works like a charm and plugs directly into the 7-pin trailer connection by the hitch. The aux port on the 7-pin has a 30 amp rating and this model of Viair has a max of 30 amps. The 7-pin dongle for the Viair is an accessory. Fills my 34x10.5 R17 tires from 20lbs to 35lbs in about 1 minute per tire. Sweet!
+1. This is what I went with. I saw no need for exorbitant on board air installs I've seen available.