We do this a lot in the summer time and it's yummy. We typically do small rounds because they are easier to handle. We form our crust, pop them on the grill until they look done on the bottom, then flip them over and add, in order, cheese (used as glue), tomatoes and seasonings, and toppings. You will have to play with the heat, since grill temps vary, but we usually do ours at a medium hot. They bake very quickly.
Good luck! Let us know how it turns out for you.