Bought a 5th wheel.. now I need a truck

Whatever one you decide on I would get a sliding hitch.

I recommend a 1 ton SRW. My fiver in signature below weighs 12280 loaded with a 2400 lb pin weight. I had a 3/4 truck and was exceeding the truck payload (gvwr) by 500 lbs when loaded up so I moved to a 1 ton and am now within all safe specs of the truck.

Full ton SRW

That half ton 6.0 Vortec would be right at the max capacity of what I would ever want to use it for. It will be downshifting a lot. If you won't be making many trips per year you might be able to make it work.

Better to go with a full ton with a bigger engine though IMO.

I am a firm believer that you can never have to much truck. I have never had a Ford but I did have a 2003 2500 Chevrolet with the 6.0 and I found it to be gutless and fuel hungry. The 7.3 Powerstroke is known to be a reliable workhorse so that would be my choice between those 2 trucks assuming it was well maintained and everything else being equal.

I would go with the 7.3 diesel and I would recommend a slider hitch given the design of the front cap on that Jayco.

I'd go with the 7.3 and a slider. you'll have all the power you will need with the 7.3 and since your 5ver doesn't have the rounded front corners, the slider will help in tight spots.

Nice RV!

2011 or newer F350 or 3500HD SRW. Long box so you don't need a slider hitch.

The hitch weight will be closer to 2300 lbs. Your curb weight is closer to 10,000 lbs. Our advertized dry curb weight was 9,700 lbs. Actual weight out the factory was 10,014 lbs - no propane, no slide awnings, all tanks empty and 1 battery

You need payload for fuel, passengers, hitch, truck options, trailer options and anything you put in the truck box.

Similar trailer - my CAT scale weight (two passengers and full tank of fuel - black and gray tanks empty - water tank about 1/3 full)
Steer Axle - 4900 lbs
Drive Axle - 6060 lbs
Trailer Axle - 9220 lbs
Gross Weight - 20,180 lbs

Truck GVWR - 11,600 lbs
Trailer GVWR - 12,380 lbs

My truck weight with me in it is about 8000 lbs

I would probably agree that the 7.3 would do the job, but I think that pin weight is suspect. I think it's going to be north of 2k once you're fully loaded, which means you're approaching 1 ton territory. Either would probably be ok, but the 1 ton will make for an easier tow and less stress.

I have just prepped my low mileage 2003 F250 to haul a 12K/2K fifth wheel. You should be very careful when considering any used diesel pickup truck.

I put custom Curt frame mounts with in bed rails, Air Ride rear suspension, TruCool tranny cooler, a 16K B&W Patriot fifth wheel hitch and a Curt wiring harness. I also am installing a set of gauges with boost, pyrometer and transmission temps to go along with a D-P Tuner F-5 chip with 60 hp tow mode and 80 hp econo mode. I'm up to $1200 in expenses already. I've still got to change the transmission filter and 20 quarts of ATF and flush the radiator while replacing the thermostat and its housing.

Any used 3/4 ton diesel should be taken to an independent diesel shop and a complete scan done on the engine to make sure it's 100%. (Just a set of injectors can run you a small fortune.) They should carefully checkout the transmission, as 3/4 ton trannys ($3K) are not long life items. The suspension and brakes should be carefully checked out, as they need to be at 100% condition for a tow vehicle. Brakes can be especially important.

I don't mean to scare you, but getting a tow vehicle in shape is not a cheap proposition. Scariest thing is the price of fuel injection parts and $110 per hour labor rates. I'm fortunate to have a great independent shop that's reasonably priced.

Well you should be looking at at at least a SRW 350/3500. Many before me have stated that yes we tow a 12,000# GVWR 5er with a 2500, even early 2000's, BUT I know I am over my GVWR, while under my axle ratings.
With the age of the TV, I would get a good diesel mechanic to look over the Ford and give it some serious consideration.
I tow with a 2001 2500 Ram Cummins, but have a 5 speed manual. The autos of this vintage may need some help to pull your new rig.