Heat your grill to medium-high heat (propane or charcoal will work). Brush the grill with a little oil to prevent the peaches from sticking.
Lay the peach slices on the hot grill and cook for 2-3 minutes per side, or until the peaches are tender and have grill marks. Remove the peaches from the grill and set aside.
Roll out your pizza dough while the peaches are cooking. Make sure the dough will fit on your grill, rectangular pizzas are totally allowed.
Lay the dough on your hot grill. Cook for 2-3 minutes on the first side until the bottom of the pizza is set and there are grill marks. Carefully flip the dough over and cook for 3-4 minutes.
While the second side of the pizza cooks, brush the top of the pizza dough with BBQ sauce almost all the way to the edges. Sprinkle the pizza evenly with mozzarella cheese. Add the pork over the cheese, spreading it around the pizza in dollops. Then sprinkle the cheddar cheese over the pizza, and lay the peach slices all over the pizza.
Cook until the bottom of the pizza is set, has grill marks, and the cheese is melted.
Remove the pizza from the grill and onto a baking sheet or cutting board.
Sprinkle with cilantro and cut into pieces. Serve immediately.
I cut my pizza into triangles, but that does kind of give wonky edges if your pizza is rectangular. I'd recommend cutting square-ish slices.