I'm with RangerDF. I've had great success doing pizza directly on the cooking grates of my gas grill. I usually buy a nice ball of dough from a local pizza place for $4 or $5, pick off a piece, roll it out thin and coat it with olive oil before starting. Grill one side to desired doneness, flip, add toppings, and close the lid so the cheese will melt. All your toppings need to be precooked or edible raw.
If you can find it, I highly recommend the book "Pizza on the Grill" by Elizabeth Karmel and Bob Blumer (Taunton Press, 2008). Lots of tips for both charcoal and gas, and some great recipes. Good luck!