Efficiency wise, a trailer hitch is one of the poorer places to mount a mobile antenna, especially on a van or SUV. Where ever you mount it, keep the coil as far away from the body as possible. Mounting it atop a long post isn't an answer either. If you need some hints, visit my web site, and look under Installations. BTW, you can have a mount made cheaper than you can buy one. There are several in the aforementioned article.