Yup, a Ranger will handle a slide-in just fine if you equip it properly. You DEFINITELY need a set of rear airbags to handle the weight though (I have a set of Firestone sport-rite airbags with an onboard compressor setup). However, you will be slow on the hills and you're going to average roughly 10 - 12 mpg so you mind as well just find a cheap F250 if you're doing it for fuel mileage reasons. Compactness? Well, you're still 9+ feet tall and your stability isn't exactly stellar in anything less than city street situations. You will not fall over per se (trust me, I've had mine on some retarded angles offroad with the camper, and actually STOOD it on the rear bumper backing out of a nasty crossditch and hitting the brakes in another, I was looking directly up at the sky!! What saved me was the ATV trailer acting as a catch behind me, and it was dug thoroughly into the ground, but it still nearly fell over to the right! Scared the crap outta me none the less), but it will feel like it whenever you're trying to turn on a decent hill.
If you're looking to DD a compact pickup and haul a camper occasionally on the side, then yes it will handle it fine. I had mine mounted on the truck from about a month old for about 8 months there after due to my work schedule. A 7' slide-in will be fine for you, but IMHO it is far too cramped for a second person unless you're very friendly with them. I didn't have any issues fitting in the bed though, even at 6' tall I was able to sleep comfortably in the overhead bunk - and the camper's still parked out front of our house and gets used as a guest shack when we have too many people over lol.
As for weight, my camper weighs approx 1200 lbs and the ATV trailer and quad weighs about the same loaded, maybe a touch heavier. At 70 psi in the bags (90 psi max) it actually sat 1" HIGHER that stock when loaded right up - full fuel, spare gas cans, propane, food, gear, you name it! I kept the tranny in drive (O/D off) and kept my speed to 90 km/h to keep the rev's in check, but it drove perfectly fine. It wasn't no sports car like a 1 ton diesel when loaded, but it held its own fine. HD tranny cooler would be a very good idea though to keep your truck cool on the hills.
Here's a couple of quick shots of my setup: