Brush chicken breasts with extra virgin olive oil then sprinkle with salt and pepper. Grill over medium-high heat for 3-4 minutes a side, brushing grilled side with BBQ sauce after flipping once. Grill ears of corn, rotating occasionally, until evenly charred. Remove chicken and corn, let cool slightly, then chop chicken and slice corn kernels off cob and set aside.
In a very large bowl add lettuce (may need to do this in a couple batches.) Use a pizza cutter to evenly chop lettuce into small pieces then toss with tomatoes, black beans, red onion, cheeses, tortilla chips, chicken, and corn. Drizzle with light ranch dressing and bbq sauce (or your favorite dressing) then toss and serve immediately.