I usually heat MPO with top stone only for about 15 to 20 minutes or thill top stone reach desired temperature then I place place MPO bottom stone on the grill under MPO and heat for another 15+ minutes.
Thonight, I did a heat test by using only two burners only (25,000 btu total) using the same setup I used in my last bake, and heated MPO with both stones in, for 40 minutes, to my surprise, bottom stone was in the low 800s F and top stone was in the high 800s F.
My grilll knobs were hot, but not to where getting melted.
As time permit this weekend, I will try 100% AP first instead of 50%AP /50%caputo.
To get the blister effect, still remain a challenge on gas grills, since the flames are way below MPO. I am expecting MPO2 to do better in this area due to it's sloped sides and hotter top stone.