We're not going but we have spent a night or two in the rally park. Be sure you take some good jack pads - even on the gravel sites we broke our 3/4" plywood we used occasionally for jack pads.
Depending on what site you wind up in, you could have a real challenge trying to level. I made some jack blocks some time ago out of 3/4" plywood and a 2x4s. Looks something like this:
======= 3/4 ply
| | | 2x4 on end
======= 3/4 ply
(If this gets messed up when posting, I'll take a picture of mine if anybody is interested)
I don't need these very often, but they are the cat's meow when you have a really sloping site. If my math is correct, this will give you the equivalent of about 5 extra inches of jack for leveling.
Of course don't forget to only use these on the front - don't even think about lifting the rear wheels off the ground