Timbren suspension enhancements are a great no maintenance option for extra load support. After the initial suspension sag of 3/4" to 1" the Timbren assemblies will contact the axle and should hold the truck at a level height front to back.
The trade off is that you will not be able to return the truck to a stock ride height with the camper loaded and you will not be able to level side to side with them Timbrens. If you will need side to side leveling and want adjustablilty an air bag kit may be the correct option. If you want a no maintenance kit the Timbrens are a great choice.