Free the wiring harness up in the back for the lights, unhook your filler necks, remove all the bolts (with a wrench or a grinder and punch), then get a case of beer for the three friends that help you lift it off the chassis (one friend will work, but it's easier with four guys).
You can turn it upside down and lay it on the ground flat or get a couple of saw horses and set it right side up. If you are going to put it back on you'll want to make some marks from the bottom to align things a little faster.
Good luck,
Paul