The non-controversial portion: In full size trucks, the camper are secured with "belly bars". This is a steel bar which runs under the frame ahead of rear wheels (in some cases, people run a second bar behind rear wheels). The bar is fastened to the frame (clamped/bolted) and to the camper.
Can versus May:
If you look at example camper:
http://www.northern-lite.com/truck_camper_lite_610.php, the empty weight is 1,050 lbs, 14 gals water = 140lbs, clothes, food, etc. and you will have exceeded the 1,260lb max payload of the Ranger. And you, your sandwich maker and the pet aren't in yet.
So, from a legal (insurance) perspective, you
may not.
Note: This is where the 'New' Ranger with its 1,200kg payload is going to kick; more than double our existing Rangers.
The towing limit for your Ranger is 1,580lbs, so this camper might not be any lighter than the trailer you towed (assuming it really was lighter than your limit).
Now, the
can part: 2.3l/5spd/3.73, probably has a 7.5" with 9" brakes. Upgrading to an 8.8" with 10" brakes (get Aerostar finned drums) with 4.10 or 4.56 gears would help a lot along with 1,750lb HD aftermarket springs and maybe higher load ranger tires (just have a kidney belt when driving without the camper

). Unfortunately, the upgrades reduce your legal payload capacity as their heavier weight counts against your GVWR.
The real answer is: You need a bigger truck than a Ranger for a camper
