Boy these guys are a lot of help...
Pick up a case or two of beer and a couple bags of ice, and call several neighbors/buddies and invite them over for a cold beer on your way home. Grab a pack or two of brats, buns, and chips and have lunch afterwards. A little beer goes a long ways! And, the ribbing you'll take for inviting them over to help unload the compressor, will be worth the help. (
Even if you do have to feed them!)
Personally, I'd haul it on the trailer, lower to the ground, easier to unload if you can't find help. I do it all the time with the lawn mower trailer and the highlander and I have 3 skid steers, 2 two all terrain forklifts, and numerous flat bed trucks, at my disposal, as well as a pickup to drive. (
Of course the pickup has 11 inches of lift and 37 inch tires on it, but...)
Whatever you haul it on, I'd haul it standing, then lay it down and slide it out over the end gate and stand it up on the ground/shop floor. (
Assuming you have some way to tie it in a standing position!) The short time it will be on it's side in this manner of hauling/unloading it, won't hurt anything, whether it has oil in it or not. If it's new, I'm going to guess the oil is not in the compressor, so don't forget to pick up a quart of 30 weight non-detergent on the way home too. Synthetic compressor oil can't be beat, but you need to seat the rings first.
If you do lay it down to haul it, with pallet at the rear, be sure to tie it securely so it can't slide forward and wreck things... Like the compressor, belt guard, air lines/switches, the front of your truck box. I know I probably don't have to tell you things of this nature, but I've seen some pretty intelligent people do some pretty stupid bat guana in my day, and I'm jus sayin... The time spent tying it securely so that it doesn't slide when some little old lady pulls out in front of you, is never wasted!