Towing camper with van. What rating hitch should I purchase?

Thanks for the replies everyone! Definitely good feedback. I figured class 3 was better option but this solidified my choice.
I also knew that I was going to be maxed out (or very close) with supplies in camper/van but some of your info has me thinking I need to just purchase a truck with better towing capabilities sooner than later. The last thing I want to do is ruin the transmission on my wife's van in a year or two of camping.
(sorry for the cross post).