What is a safe towing weight for a 2004 Nissan Xterra?

My parents are going out of town for a camping trip and are planning on towing a camper (approx. 2800 lbs.). Their only towing vehicle (1998 Plymouth Grand Voyager) was totalled in a accident on Sunday morning and so my boyfriend offered his '04 Xterra for them to drive. He is concerned, though, about the weight of the camper. He towed a "medium-sized Uhaul" when he moved about 2 years ago and said it almost ruined his power steering. We looked up towing capacity and it should be safe but I would like to know for sure. Thanks!