My Fleetwood camper had a 33 gallon FW tank. We could go for a 3 day weekend including 4 showers, rinsing off the kids, washing dishes, and drinking water and still have some left over.
I would not recommend an F150 or any other class 1 truck for a TC. Yes, a dually is necessary for the bigger campers, it's recommended for all but the smallest lightest campers. Truck's rated payload is a marketing game. They will say it has "up to" such and such a number. That usually means a stripped down 2wd model with no options. An actual truck's real payload is listed on the door sticker.
Campers are heavy, water is heavy, people and gear add up. If you are considering a hardside camper with big tanks you should be looking at a 3500 single rear wheel truck as an absolute minimum. But, you will likely be happier with a dually. I was.