Lazyday,
If I understand what you are saying, the when your camper is level the height of the hitch ball matches that of the tongue. However, when you hitch the camper and truck together the weight of the tongue causes the back of your truck to be depressed. Is that correct or did I not interpret you correctly?
If I'm correct then getting an adjustable hitch will not help the problem. To correct this you have several options. You can move stuff in the camper behind the wheels to reduce your tongue weight (note the tongue weight should be 12 to 15 percent of the total weight). Or you can install a weight distribution hitch which will re-distribute the weight to the various axles resulting in a level truck and camper. Others have used air bags to raise the rear end but this does not distribute the weight as a WDH would.
Hope this helps.
Ruide