Best way to add a cable pass through/access in camper.

You don't really need any special boxes or conduits to get a wire through the roof. But if you have end connectors that you want to pass through large holes, or if you want several or more cables to pass through at one location, it might be the best way to do it.

But for a single cable, which you will add end connectors to after pulling, all you really need is a small hole and a dollop of Dicor. A drip loop is always recommended.