Love those Four Wheel Campers! But I'll have to agree with you, that 4-banger HAS to be cutting it pretty close. Which ever way you choose, make sure you pay close attention to the dry and wet weights of the camper. Anything over your GVWR or axle ratings are you're just asking for it.
I started off with an '06 Dodge Ram with the 5.7L Hemi and threw a mid-90's Starcraft popup camper on there. It was about 1.500lbs. wet, which is pretty light considering, and I was over my GVWR. In normal conditions I'd forget it was back there because I could hardly feel it. Throw in some sudden stops in Southern California traffic, some long grades (up OR down), and a little crosswind for good measure and you'll know real quick that the truck manufacturer's don't just pull those ratings from thin air.
Just a friendly piece of advice from someone who did it bass ackwards - find the camper you want, then buy the truck to haul it in - not the other way around. Too much camper for too little truck and you put your life in danger, as well as everyone else you're sharing the road with.
Good luck in your quest!
