If you haven't done much RVing, then the minimal investment suggestion is a very good one. Almost everybody can enjoy a long weekend in a beautiful park with excellent weather. Find out if you can stand a week of rain, puddles and mud. It'll eventually happen.
If the only vehicle you own now is a subcompact sedan, then a Class C is the least expensive way to get into RVing, and if that subcompact is towable, even better.
But if you already own a suitable truck, need a massive truck for business, etc. then a TT or Fiver starts to make sense. My cousin had a Yukon. I think it was a 4WD with 5.7L engine. He bought a single slide 26-ft TT and made a number of trips with that rig, staying within Florida. After one trip to the Smoky Mountains, he traded for an F250 diesel. So... my quick look shows 4.8L V8 for your truck. If so, that 24-ft limit you mention is what I'd see as maximum even though that page I looked at said 7700-lb towing. They're usually overly optimistic, and that towing rating figures a truck that's essentially empty. Put 1500 inside the truck and towing is now 5200, etc.
They started having the 6.0L V8 in those trucks along with a six-speed automatic. A friend from Oregon has that one, and has pulled a 28-ft TT all over the country. He's happy and doesn't have a diesel which he feels is an expensive trouble prone setup.
V10? An outstanding power plant.
But first let me say: NO Class C (E350 or E450 chassis) EVER had the Three-Valve engine used in later model F-Series and the Class A chassis. 3V has 50-hp more, but the TORQUE difference isn't anywhere near as much.
V10 came out in 1997. 1997-8-9 were the same engine, and it's the one that became famous for sparkplug thread problems. Not just in Class C's - every "Modular" Ford engine was that way, V6's, V8's, F-Series, Class A, every one.
In the 2000 CHASSIS MODEL YEAR, Ford changed the heads, calling them "Performance Improved" since rated HP went from 275 up to 305. They also put a proper number of sparkplug threads in the "PI" heads. So, my suggestion would be to avoid a "2000" RV that's actually on a 1999 Ford chassis. The Ford label in the door jamb will tell you that.
Unfortunately, some of those PI heads had plug holes machined just a pinch off and there were a few isolated plug issues. Nothing, by the way, like Ford had with early Three-Valve heads...
Then Ford discontinued the 4R100 transmission and phased in the 5R110 better known as TorqShift. It's along the lines of GM's legendary Allison (some say better) and has Tow/Haul mode. This lets you have Overdrive under conditions that 4R100 can't handle without downshifting. That happened sometime around 2005 Chassis Model Year.
Finally, in 2008 Ford changed the front end "look" to the "dump truck" style. But they also increased the capacity of the Front Axle and Brakes, plus a few other tweaks.
So, those who say "Ford hasn't changed E-Series since 1992" are misinformed.
1997-99 - I personally would avoid those, but many here have them and the plugs have not been a problem. I've driven F-Series from 1999 and 2010 and couldn't feel much difference between the 275-hp and the 362-hp engines. TorqShift was nicer than 4R100, though.
2000-2004 - safe bet. This is what we have and it's been very good. Smooth, quiet, powerful, decent ride, doesn't wear tires.
2005-2007 - If it has "Tow/Haul" on the end of the Shift Lever it's TorqShift, and past those years of isolated plug problems. If you can score one in your price range, it'd be worthwhile to stretch a little.
2008 - up - With Ford shutting down the E-Series VAN line, this may be about as good as E is going to get. Very nice, almost certainly out of your price range.