I've had a '97 2wd 302 XLT for 16 years. It is the most reliable vehicle I've ever owned. It has the 4R70W trans and towing package, and is rated to tow 6850 lbs. What they said about being awkward to work on is partly true - the engine compartment is TIGHT, but with patience most things are no worse than your average FWD car. Underneath, it's just a truck, easy peazy. Mine has 213k miles.
Lets see...common issues...
The HVAC blend door insie the dash unit gets flakey or brakes. It's kind of bitch to get to, but there are fix kits for it cheap. The 4R70W has a spring on the 1-2 shift selonoid that breaks and gives you hard 1-2 shifts, feels like a shift kit. Upgraded parts are available from Ford for about $30. The trans likes to stutter going into OD if it needs a fluid change or isn't running full synth Mercon V. Once those two items are done, it's a tough trans. If you see one with a blinking OD light, though, that means it needs a rebuild or will shortly. If you hear a chirping noise from the front top of the engine that sounds like serp belt slip, it could be the cam position sensor. It's easy to change but once they start chirping it's on it's way to a failure which can be bad. There are 2 sensors in the EGR system that like to fail - DPFE and something else - that will give you a CEL for the EGR function. A little awkward to change, but they'r right on top of the motor. One is $20 and one is $60 I think. The metal tube from the psg manifold up to the EGR likes to develop a hole and makes a sound like the engine tapping. New tube is about $90 and not bad to change. Ball joints are wear items and a mild PITA to change. The rear flat panel windows develop leaks that leave the carpet in the back wet, but the leaks are cured by simply tightening down the nuts on the window mount studs. It's only a problem if you let it go long enough to cause damage. Oh, cruise control buttons melt on trucks that have lived in hot climates. New replacements are $160/set, ebay used pieces are about $60/ set, and none exist in junkyards.
All in all, they're one of the best things Ford ever built in my opinion. If you wanted a 2wd I'd make you a deal on mine. It has some minor issues,but I'd tow our camper to Cali in it tomorrow.
FOr more than you ever wanted to know, particularly about the 4x4 mod possibilities, check out explorerforum.com
If you have any other questions, I've spent a lot of time with them, just ask.
EDIT: I read reread your post - I've slept in mine once and it was okay. with the rear seat folded flat you have exactly 72" from the back of the driver's seat (all the way back) to the inside of the liftgate. I'm 6'2" so I ran the psgr seat all the way forward and it was okay. Interior height wasn't quite enough to sit bolt upright but wasn't bad. I made an interior bike rack with a flat board and some fork traps, but ceiling height is low enough I have to pull the saddle/seat post to get my bikes in (58cm road bike, lg dual sus mtb.) The wife's bike fit fine without. You can easily lay a single bike in the back with the seats down and still have room for some other gear - a duffel, small tent, folding chairs, and a cooler.
Mine has always done well on gravel and minor off-highway use, but it's mostly a pavement animal.