I never felt that if the truck came down to around level with the camper that I had a problem. I just drove it. Three inches might be right around level with an F250, I don't know your truck. Likewise, if it was off the bump stops that meant the springs still had room to work. Much of what direction to take to modify your truck depends on what you do with it besides carry a camper. If it's dedicated to the camper, I would go with added spring leaves. If it's a daily driver empty, I might go with air bags. I would definitely consider front and rear anti-sway bars - just adding a rear bar can make it oversteer too much in wet or slippery conditions and actually be quite unsafe unloaded.
It would help to know how heavy your camper is.
Brian
