My dad had a few when I was growing up and I've owned two. Dad's were Chebbys, mine were Fords. I had a '97 E150 with the 4.6 and an '06 E150 with the 5.4. I towed the same car on the same trailer with both of them - probably about 4500-5000 lbs with the car, trailer, tires, tools, etc. The 4.6 got the job done, but you could tell it was trying while the 5.4 didn't have to work quite as hard. I have no idea what axle either one of them had, but other than needing to take it easy up the hills, they were very well-mannered on the road laden and unladen.
The Fords eat up front end suspension, so be prepared to do upper and lower ball joints and use good parts. For some reason the dash A/C works okay by itself, but as long as the rear air is at least on its lowest setting you get colder air out of the dash vents. That was true on the Chevys and the Fords, oddly. Fords also are prone to getting vacuum leaks in the lines that control the doors in the HVAC box. They will fail-safe to the defrost position and a sign that they're starting to go bad is that they'll work normally until you get heavy on the throttle and then all of a sudden it'll switch to defrost. I drove the last van for about 30k miles like that. Fords are also pretty good about being pre-wired for brake controllers so all you need to do is get the adapter harness to plug into the Ford connector and then attach the mounting bracket to the dash. My experience with Chevys is a bit dated in the GMT400 era where you were pretty much on your own.
They're pretty good to travel in, especially while trailering. If you put most of your luggage in the car that you're towing and then remove one or both of the rear captain's chairs, you get a lot of room inside to be able to spend the night in a parking lot or camp at a racetrack. Every conversion van I've seen has a third row that will fold flat into a pretty decently-sized bed, although at 6'3", I found that I needed to sleep diagonally. The high-top vans are a pain in the rear if you ever want to pull it into a regular garage or if you often need to utilize parking garages, but it is pretty nice to be able to stand up, plus you get a little extra storage overhead.
For camping purposes, I got some mosquito netting from one of the chain fabric stores, cut sections for the rear and side barn doors, and then used magnets to secure it over the openings. I also put aftermarket head units in each van and having a wireless remote for them was pretty nice. Perhaps now with phones and bluetooth speakers, that wouldn't matter quite so much.
They are vans and that means that pretty much every repair procedure is going to start with "lift body off of frame for access to engine". It took me about 4 hours to change the 8 spark plugs and most of that time was spent on the two that were closest to the firewall of course. The Fords use this weird clamp that was designed by Satan himself to connect the air filter to the MAF sensor and I can almost promise you that at some point after doing maintenance under the hoodlet, you'll find that you didn't get that reconnected properly. Other than that, basic maintenance is pretty straightforward. No need to break out the ramps or a jack to change the oil or trans fluid. Brakes and suspension aren't anything fancy or expensive.
Unless you've got some huge enclosed trailer you're trying to drag, I wouldn't bother trying to find a 3/4 ton conversion. They made some E250 conversions, but they're few and far between. The later Chevys were available with rear doors on both sides of the van, which is nice, and they also had AWD as an option. I found that the RWD vans always did alright in weather, although I did need to have it pulled out of mud once or twice when it was laden with a trailer.
