I would recommend that you buy a Wilson5000 magnet mount and get it over with.
Mounting CB antenaes on corners of vehicles at best if your swr are low puts you recieving and transmitting directionally.
Mounting an antanae square on roof with your swr's low puts you omni-directional.
Big rig over the road trucks obviously can't mount or most won't mount antenaes on roof.That why lots of them run dual antenaes(one on each mirror)for better reception/trans and also makes rigs look sharper.
Boone