Separate the pancetta slices so they are easily accessible (they tend to stick). Slice the cantaloupe into thin slices. If you want to be fancy, use a biscuit cutter to cut the cantaloupe into "pepperoni rounds". Slice the onion and mozzarella and arrange the ingredients on a platter so you can easily build the pizzas on the grill. It is important to have everything in its place before you begin to cook.
Place the arugula into a salad bowl and set aside. In a small bowl combine the olive oil, vinegar, dijon, garlic, salt and pepper. Whisk to combine and set aside. (Don't dress the greens until you're ready to serve -- otherwise they will wilt.)
Preheat the grill to 400 degrees.
Dust your work surface with flour. Separate the dough into 4 equal portions and roll each one into a ball. Place one ball of dough on the work surface and use a rolling pin, lightly dusted with flour to roll the dough into a disc about 1/4"- 1/3" thick. Set the dough onto a baking sheet and continue rolling out the other balls of dough.
Assemble these ingredients by the grill: pizza dough, olive oil (and pastry brush), pancetta, cantaloupe, mozzarella, onions, parmesan.
Place a pizza dough on the grill. Sprinkle with 1 teaspoon of olive oil and quickly brush the oil over the dough with a pastry brush. Lay one quarter of the pancetta over the dough in an even layer. Top with a quarter of the cantaloupe, mozzarella, onions and parmesan cheese. Close the lid on the grill and cook for 6-7 minutes. Monitor the grill in case of any flare ups. Use a large spatula to transfer the pizza to a baking sheet or pizza peel. Continue with the remaining pizzas. (note: depending on your grill size you can cook 2-4 pizzas at a time, but the longer the lid is up, the more the grill will cool and it may take some time to get back to a high cooking temperature.
Add the dressing to the arugula and toss.
Serve pizzas individually with a nest of arugula on top, or cut into wedges and top each wedge with greens.