Horizontal antenna

You should be happier with one antenna, because your field strength pattern is in a circle instead of a long oval. Duals are good for talking ahead and behind you...if the other guy is directly ahead or behind you. Me, I gotta talk to everybody!
CB waves are vertically polarized and any tilt to the antenna tilts you out of the alignment to the antenna you're trying to talk to. Directly flat, you have a 1/4" high antenna, in a sense. A whip can be done, but is problematic due to height and nearby metal affecting your SWR.
There are negatives to magnetics but they do work. I like my Wilson 2000 for all-around performance. I intend to build a better one than that soon. The thin wiring coils in factory antennas never seem to outperform our local redneck garage units.

 

Out here the 4X4 Clubs I used to run with would not let you use a 102 whip ant. When you are rock crawling that ant becomes just that a whip and anyone close by could get a nice whack.

 

just tie some rope to the top of the antenna and then tie it to the car some how so it wont whip

 

If you 4 wheel with a loose whip, I'd think that beating the heck outta the rig would be more of a problem...then loosening of the mount. Good thing about a 102 is you can't hurt it. Even cops used to run them ...back when they invented dirt.