My antenna is long, magnet-mount & seems to get great reception. So I decided to mount on back bumper -- without drilling any holes.
I used a 4x4 post mount (a u-shaped metal), bending one leg backward about a third from top (creating a backward "hook"). The other leg I cut a large V-notch (from the existing center bolt hole), and fold abt half-way inward to "pin" bottom of my antenna.
The "hook" goes over the bottom rubber gasket (between rear lights & plastic bumper) quite securely. The black electrical tape is to prevent scratching body paint (to be replaced with...above). This provides a metallic base for my antenna's magnet mount. On long trips I further "secure" this metal base to bumper using "eartquake"-gel, which sticks very well, easily removed, and does not leave any residue on bumper.
To prevent antenna from whipping, I use a short stiff plastic line fished between holes on the plastic vent above rear lights -- and just threading antenna through the plastic line.
Everything goes on&off real FAST & EASY (Mic mount is not removed -- when it is all black, not noticable imo). Sorry, pic is after 3 days at Pismo -- covered in sand!
