Cook the rotini pasta in a large pot of salted boiling water until al dente, per package directions. Drain thoroughly and rinse briefly under cool water to stop the cooking process. Allow it to cool completely.
In a very large mixing bowl (one that can handle 18+ cups of salad), combine the cooled pasta, chopped pepperoni, finely chopped cherry tomatoes, cilantro, red onion, yellow corn, white corn, black beans, black-eyed peas, jalapeño, red bell pepper, orange bell pepper, and yellow bell pepper.
Drizzle about ¾ cup of the Italian vinaigrette over the mixture to start. Toss gently but thoroughly to coat everything evenly. Taste and add more vinaigrette (up to the full 1 cup or a bit extra) until the salad reaches your desired level of dressing coverage and flavor. Season with salt to taste, keeping in mind the pepperoni, beans, and dressing already add some saltiness.
Cover and refrigerate for at least 1 hour (or up to overnight) so the flavors can meld beautifully. Give it a quick toss before serving, and add a little extra dressing if it seems dry after chilling.