Standard type installation automatically plays thru your cars speakers, you tune the car radio to the FM station you select (a station not used in your area) the SeriusXM unit will transmit to that channel and is picked up by your cars antenna...
Most trailers have at least one 12 volt cigarette lighter type or auxiliary port .that can be used . You can then set the on board radio to the strongest station. The Sirius antenna can sometimes be put in a window to receive the satellite. If not you will need to put it outside.