That RC is sweet!
As far as weight, I think period literature is slightly off. My truck is listed at 39xx from the title, and 39xx or 40xx from dodge. In reality, it weighs around 4600 with me (180), a half tank of gas, and some basic tools and tie-downs.
I don't think there is really anything to avoid. Even if you buy a lean-burn truck, you can retrofit the crappy ignition to a regular system for pretty cheap. Just avoid rust and ghetto hack (
don't look at me! lol)
Check out the MPG thread to get an idea of the mileage you can expect. As usual, be wary of any claims that are less than 2, or more than 25.
For reliability, I've put nearly 40,000 miles on my truck without it not being able to get home safely, under its own power. It's a lot like a tractor. You may have to do some tinkering, but most things that break cost less than $20, and usually a $15 socket set and a crescent wrench will be all you need. And it will still run in the mean time.
If you want a road legal farm tractor, then buy a first gen, and don't look back.