We would need to know more about the truck before giving good advice.
I know that the 2011 - 2015 F-150 Ecoboost has at least 4 different GVWR on the trucks. And if you take into account that 'your' truck can be anything from 2000 to 2015 model year, it can be significant GVWR change between the years and cargo packages.
So what is the GVWR? Is it crewcab, extended cab, regular cab? Any clue as to the curb weight? If the curb weight is say 5,000 pounds while it has a 7,500 pound GVWR, then you could add a substantial amount of weight to that truck before overloading it. However most Rams are more then 5,500 curb weight, and GVWR can be just about anything?
Ford has some Ecoboost F-150's with a 2,300 pound cargo rating. That is nearly as much as some of the crewcab F-250's. Back in 1999, the diesel F-250 crewcab with 4 wheel drive, it only had a 965 cargo rating. That can be all used up with 6 passengers, leaving nothing for cargo or a hitch.
Most fifth wheel hitches come in a crate that is about 150 - 200 pounds. So that hitch is not light, and will take away from the cargo rating.
Also consider the brake size. You might have disk brakes all around, and be fine. But if the trailer plug comes unplugged from the truck, it can be a problem with a 1/2 ton truck, while a dually F-350 will stop in a somewhat longer area, but still stop.
Good luck,
Fred.