An hour before grilling, remove dough from refrigerator. Lightly coat each round with olive oil and place on a rimmed baking sheet.
Prepare a charcoal grill for one-zone cooking and build a hot fire (the temperature should be about 600 degrees). Carefully wipe preheated grill grates with a lightly oiled paper towel. Using a grill brush, scrape the grill grates clean, then carefully wipe with a lightly oiled towel again. (If you’re using a pizza stone, allow it to preheat with the grill.)
Meanwhile, in a skillet over medium-high heat, cook pancetta with a drizzle of olive oil until brown and crisp. Create a pizza station that includes pancetta, ricotta, onion slices, and arugula as well as olive oil, red pepper flakes, and salt.
To grill crusts, start by using your fingertips to gently tap center of dough to flatten it slightly. Then pick up the dough, ball both your fists, and drape top edge of dough on one fist so the round stretches down against the back of your hand. Continue to move the circle of dough around your fists so the dough continues to stretch downward into a circle until it’s about 10 inches in diameter. Then use both hands to drape it over the hot grill (use your fingers to quickly reshape the dough if it has lost its shape). Grill 1 to 2 minutes uncovered, or until the bottom side is crisp and marked. Use tongs or a spatula to remove crust from grill and place it ungrilled-side down on baking sheet. Repeat with the remaining dough. Close the grill and let it reheat to 450 to 500 degrees. Top the grilled side of the pizza with a few swirls of ricotta and a scattering of pancetta and red onion. Use both hands to place the round on grill and cook 3 to 5 minutes, covered, or until the bottom of the crust is crisp and the cheese is melted.
Slide tongs and/or a big spatula under crust and transfer it to a cutting board. Drizzle each pie with olive oil, sprinkle with flaky salt and crushed red pepper flakes, top with a handful of arugula leaves, and then use a chef’s knife or pizza cutter to cut into wedges.