I think it's crazy for anyone wanting to haul a hard side truck camper to look at a 150 series truck. It's likely that after you load the camper with water, propane, food, gear, etc. and put the passengers in the truck you would be at the limits of a 250 truck.
On the F150, you have to look at more than payload. TCs put all their weight on the rear axle so any capacity on the front axle is useless. Even if you can be very careful to pack light, don't travel with any water, don't take many passengers, and just get by, why do it that way? Just get the heavier duty truck and pack what you need without worrying.