When cooking pizza on your Grill Guru, always use a combination of a pizza stone and a plate setter with diffuser stones. Place the pizza stone on the grill. The rack is closer to the fire. So it is very likely that the temperature measured at the rack is much higher than the temperature indicated by the dome thermometer. A difference of, say, 35 degrees Celsius is certainly not crazy.
So what is the ideal temperature for baking a pizza? There is no single answer for that, everyone has their own preferences.