The standard Sirius antenna is intended for magnetic mounting on a car roof. On a fiberglass roof it needs to sit on a steel plate about 9 x 9 inches to provide a ground plane for best reception. I went with a Sirius Marine antenna which has the ground plane built in. In any case that is a sloppy installation, there does not need to be any cable visible.
Bruce Dickson 2013 Thor Challenger 37GT, 5 Star Tune, Safe-T-Plus Steering Control with Air Trim, Roadmaster front and rear Sway Bars, SuperSteer rear Track Bar, Crossfires, 2012 Honda CRV on Blue Ox Aventa LX tow bar. Full timers since Jan 2012.