Cracked the bed of my truck

I too would take a hard look at the bottom of the TC for signs of distortion. The camper itself may be flexing which would in turn flex the bed. A TC is a hybrid semi-monocoque comprised of a wood or metal space frame skinned with plywood to stiffen that framework. Similar to an aircraft with longerons (ribs or frames) and stringers then a thin aluminum skin. If the bond between the skin and the ribs (staples, tie plates or adhesive)start to fail the structural stiffness disappears and it will start to sag. That in turn means the weight of your TC is no longer spread over 4608 square inches(maybe 1psi)on a long bed. With the TC no longer supporting itself it droops over the bed pushing down in areas with little reinforcement.