IMO you shouldn't need a tool at this stage. Everyone here should know where DirecTV dishes need to be pointed based on the area they are in. So...open google maps and type in the address for your clients residence. UP is north. You should be able to immediately know whether or not you can mount a dish where you want to. You don't need the specific line because your dish, once mounted has a bit of range.

This house is in illinois so dish points southwest. Dish could be mounted on the back or the side of the house.