I cook pizza right on the grill all the time I dont use a stone I do it right on the grate lots of olive oil on the dough and you have to work fast.
All of your toppings must be pre cooked. I throw the dough on let it sit for a few minutes and look under to see if you have grill marks then rotate 90 degrees and check for grill marks. When you have the marks going both ways flip it over and start to put your sause on then cheese and toppings but go light on the toppings it seams to work better that way. By the time you get your toppings on rotate 90 again shut the lid for a minute or two and your done...And there great !!!
Pat