Me thinks this won't work...
Here's the trick. A single word.
Somewhere in the drivers door you'll find a sticker that says "Weight of Cargo Plus Passengers Should Never Exceed xxxxlbs"
You might find a second sticker, probably yellow, that says "Due to modifications added by the dealer cargo capacity has been lowered by xxxlbs"
Your sticker likely has a number of something around 1500lbs. Less anything the second yellow sticker says, if you have one.
But for this simple example, let's just stick to 1500 lbs.
This number means this is total amount of carrying weight your truck has. Or, in another way, how much weight in downward force it can carry before you overload the axles and tires.
This weight includes you, passengers, dogs, cats, stuff in the back seat, GAS (6lb per gallon) AND the downward force a trailer or fifth wheel applies to your hitch.
All trailers have a tongue weight, and all fifth wheel have a hitch pin weight. That is to say how much of the trailers weight is straight down on your hitch.
So for example, I have a 28 foot travel trailer. It weighs roughly 5500 lbs empty, probably 6200 lbs loaded. My tongue weight is around 800-900 lbs.
Let's say I put my trailer on your truck with a payload of 1500.
1500 - 900 = 600lbs remaining. Add me at 200 - now I'm down to 400lbs. Add a full tank of gas 6x(guessing) 24 = 144. Now we're down to 256. Add a wife, and a dog, plus some gear,,,, and you're over. Oh, and let's not forget about the hitch... it can weigh up 150 lbs.
There's no way I would even attempt to tow my trailer with your truck.
Let's look at some ultralight 5th wheels...
The Forest River Wildwood, 26 foot. Short, mid height. Hitch pin weight = 1272lbs
Wildwood Fifth Wheels / Travel Trailers by Forest River RV
How about the Rockwood Ultralight.... Pin weight = 1253lbs.
Now how about the Keystone Laredo ultralight?
26 foot, mid height... pin weight? 1480lbs....
Laredo Specifications for 2016
I think what you are going to find is, that if you want to keep that truck, you're going to be in 25 foot and under travel trailer arena. For instance, the keystone laredo 23 foot travel trailer... has a tongue weight (they list it as hitch) of 545lbs... Even then you would want to load everything very light.
The issue with overloading a truck is,, ,, beyond the obvious that a tire could fail, is that the truck get's squirrely.
The rear suspension ends up near it's max, it flexes less because it's loaded down, and the front of the truck lifts. Now you're driving a white knuckle machine.
Anytime some other force interacts on the trailer... such as a dip in the road, a pothole, a low side, a passing semi... the trailer IS going to move, and when it does, it's going to move your truck too. With your trucks suspension overloaded, it's lost it's ability to force the trailer back in line, or up straight.. the weight of the trailer can keep your truck listing to one side, and as it does, the trailer can begin to track to that side, pulling the rear of your truck with it... the over loaded, but light front axle goes the opposite direction, and the trailer starts to sway. This is commonly referred to as "the tail wagging the dog"
What we would like to see is a truck suspension that can positively control the trailer instead. When the trailer tries to move, the truck suspension says Oh hell no, get back here... I'm not bending or giving...
This is literally why 3/4 and 1 ton trucks are produced.
Most 1/2 ton trucks are going to have a payload around 1500lbs. Anything added aftermarket, takes away.. think running boards.
A 3/4 ton truck is going to have a payload of something about 3000 lbs.
A SRW (single rear wheel) 1 ton is going to have a payload around 4000-4500 lbs.
A DRW (dual rear wheel) 1 ton is going to have a payload around 6000lbs.
catch 22... if you have a truck with TOO stiff a suspension, it will beat a light trailer up. So you really have to match the truck to the unit.
1/2 ton truck... 25 foot and under, light travel trailer, pop up campers, tear drops.
3/4 ton truck... up to 28 foot fifth wheel, ultralight, gonna be slow up hills.
1 ton, 28' and up to a point...when you get to the big fifth wheels, you REALLY do need that extra set of E-Load rated wheels in a dual rear wheel drive. It doubles the carrying load, and really makes for a stable rear end under all that weight.
Down side? a 3/4 ton truck and a 1 ton truck when empty, ride like poo-poo. You'll dread speed bumps. Loaded? Smooth as a baby.
Funny how trucks are advertised... I know someone with a Tundra... he thinks it could pull the moon because the advertisement says "10,000 lb towing capacity" ... yet the truck has a payload of 1400 lbs. "That can't be true.. the ad says 10,000 lbs..".
NOW, with all that said, here's an interesting article on ultralights for you to kick off some extra research...