Wow, userjack6880 used the EXACT same radio I did, and possibly the same antenna mount! Here's mine:
The advantage of this and some other ham radios is the head can be removed and used remotely from the radio itself. I have a separation kit and for now I used double stick tape to put the controls on the center console. I have a gooseneck mount on the way, which will attach to a seat bolt and will let me position the radio controls anywhere I want. For the mic I use that Velcro type stuff used for toll transponders (Radio Shack carries it). The mic sits where the heated seat controls would go if I had them.
The guts of the radio itself sit on the floor under/behind the driver's seat. I noticed the floor mats Velcro to the carpet, so I used Velcro to stick the radio down. Plus, my seating position is most of the way back, covering the radio (it has a built-in fan to keep it cool when I'm talking a lot on high power). The remote head, mic, power straight from the battery, external speaker (I wouldn't hear the built-in one under my butt
) and antenna coax all plug in here.
I picked up an adjustable trunk lip NMO antenna mount. I'm able to tilt it in so the antenna doesn't point off to the side, but with only one axis of adjustment it still leans back a lot. I didn't feel like dropping $50 more on a more adjustable mount to get it perfectly vertical. The antenna is a Comet tribander (144/220/440 MHz) I saved from my last car.
I mounted it far back on the trunk lid. Though more forward might be better theoretically, this way the antenna never bangs into the roof, and doesn't scratch the paint.
And that's it! My radio can run up to 45 watts, but I don't need more than 10 to hit my local repeaters reliably, despite the compromises I made in the antenna installation. Even 5 watts would work, but 10 is more reliable.
Lessons that could apply to CB - Larsen makes an NMO mount antenna that would work on CB frequencies, and you could mount it the same way I did. A handheld radio running off the lighter might work best, given the challenges of mounting a mobile radio in this car. Remote heads aren't common in CBs that I'm aware of. Or you could just get your ham license and use better radios with better range.