I've just been using one of those stick on discs mounted on the top of the dash near the center stack and the standard mount / suction cup. It works real well. It doesn't fall off going over rough trails because it's pretty much vertical. I also have a RAM for my mountain bike, but it just isn't needed in the jeep and I don't really want to drill holes in the dash. Best of all, I can remove it quickly and easily when I'm away from the jeep without a top. The only thing that's left is the disc, but it's black and blends in with the dash. I've taken lots of complaints over the years of vehicle break ins because just the mount was left on the dash so the vandals thought there must be a gps or something to steal even if there wasn't.
Support the sport. GLFWDA.org