How to mount a ski box

[sakovits]

I recently bought an 08 Frontier, crew cab with a short bed and trying to figure out how to install a short Thule ski box while still figuring out how to provide some protection from the weather if I am storing things in the bed. The truck does not have the factory roof racks and would still like to get it in the garage when done. Some thoughts were a cap with rails, a rack system with a tonneau cover or a fiberglass tonneau with rails. The ski box is about 6 inches longer than the bed (without the tailgate/extender down). Thanks for your help!