Slide In Camper Weight

[Travelling Three]

We have a 2016 Chevy Silverado 3500 diesel dually, eight foot bed. The pay load rating is 5,000 lbs. We are considering purchasing a slide in camper for a trip to Alaska but the ones we are looking at exceed 5K lbs pay load. Do I need to beef up the suspension on a already heavy duty truck or am I missing something in the weight figures? We currently have a 16,500 lbs Montana 5th wheel which the truck pulls with no effort. Thanks for educating me on this subject!