Preheat the oven to 450 degrees F. Put a jelly roll pan or half sheet pan in the oven.
In a large mixing bowl, combine the fingerling potatoes, onion, bacon, and rosemary leaves. Add 1/4 cup of olive oil and season with salt and pepper, to taste. Toss together to coat with olive oil.
Take the preheated jelly roll pan out of the oven and drizzle some olive oil over entire surface. Cut the dough into 2 pieces and reserve 1 piece for another use. Stretch the pizza dough out so it is just bigger than the pan, then lay it inside the pan so the dough comes up the sides to form a crust on the rim.
Pour the potato mixture onto the pizza dough, then sprinkle with shredded fontina. Bake for 20 to 25 minutes until crispy and golden, about 20 to 25 minutes. Garnish with arugula and drizzle the lemon juice over the top. Serve immediately.
In a small bowl, combine the yeast, sugar and water and stir gently to dissolve. Let the mixture stand until the yeast comes alive and starts to foam, 5 to 10 minutes.
If you're using a stand mixer, combine the salt and flour to the bowl and pulse a few times to mix. Add the yeast mixture, at the lowest speed, until the flour incorporates. When the dough starts to come together, increase the speed to medium and mix until the dough gathers into a ball. This should take about 2 minutes. Add the olive oil and pulse a few more times. Stop the machine periodically to scrape the dough off the hook. Get a feel for the dough as you're making it by squeezing a small amount together between your thumb and fingers. If it's crumbly, add more water, if it's sticky, add more flour, 1 tablespoon at a time. Turn the dough out onto a lightly floured surface and fold it over itself a few times, kneading until it's smooth and elastic.
If you're making the dough by hand, add the yeast mixture to a large bowl and stir in the salt and the 2 tablespoons of olive oil. Then begin stirring in the flour. When the mixture becomes too stiff to stir with a spoon, knead in the rest of the flour by hand, adding just enough so that the dough is soft but not too sticky. As you work, squeeze a small amount of dough together between your thumb and fingers. If it's crumbly, add more water; if it's sticky, add more flour, 1 tablespoon at a time. Knead until smooth and elastic, about 10 minutes.
Form the dough into a round and put it into a lightly oiled bowl, turning it over to coat the dough entirely with the oil. Cover with plastic wrap or a damp towel and let it rise in a warm spot (i.e., over a gas pilot light) until it doubles in size, about 1 hour.