This comment is as unscientific as any you've ever seen on here, but I can't imagine towing a 5000# camper with a Jeep Liberty. I pulled our camper home from the dealer with a truck rated at 5000#, and had white knuckles after pulling it the 10 miles home. And that was at no more than 40 mph, so no wind resistance to speak of. It never left the driveway again till I got a bigger truck. Give it a good test tow before you buy it.
Mvander mentioned payload. That will be critical here...study it. Everything in your Liberty, beyond 1 rather small passenger and about a 1/4 tank of gas, is considered part of the payload, as is the tongue weight of the camper. Payload gets maxed out in a hurry!
Again, a simple test tow would have told me of my mistake, even though at the time I knew ZERO about weights.