Lifting the body isn't exactly hard, but it isn't easy either... Me, My old man, and a buddy of mine can move beds around by hand pretty easy, cabs get jacked up with a 4ton floor jack (or a ?ton bottle jack if the floor jack won't do it) then just block it up with 6x6's, should be able to lift it a corner at a time... but there will probably be a ton of wires attached to the body on something that new (newest thing i work on is Dad's 01 F350 7.3 powerstroke... and it's only had 2 things done to it, some wire that came loose, and I've had the front bumper off once, trying to figure out how the brushguard i got him mounts...)

Personally, I'd look and see how many wires/bolts there are to hang up on if you lift the body, and then decided if it's really worth the trouble, you can get most of the frame by just crawlin under...