Some teardrops can have what is know as a T rail track installed. Its just a front to rear channel to attach the towers and crossbars. My NuCamp Tag Boondock came with shaped (curved) rails installed at the factory, as were the Yakima cross bars. Check with your manufacturer how they would attach cross bars And do they sell an aftermarket pr recommend one. Some rack systems, like Yakima and Thule have "feet" that are the base of the tower and are custom to the roof shape of the vehicle or camper (or pickup truck rear cap). Thus you could buy a fit kit that just sits flush to the camper roof and bolts thru the roof. You need to plan accordingly as to precicley where the feet and towers need to be, cause you are drilling holes thru the camper roof. You would mount the feet, install the towers and crossbars. I would recommend the Yakima Skyline tower system as it uses a cam clamp system that allows easy removal of the tower and crossbars.