You are correct in thinking that a fiberglass antennae might shatter. Although I do have one on my Jeep, as a truck driver I prefer a steel mast on a coil wound base, such as a Wilson Trucker 2000 or 5000. I will soon be changing out the 'glass for the Wilson.
Wilson & Firestick, are good, usually set fine right out of the box. I have a fiberglass-non tunable, on a spring, works great. Mounted to the stare tire stop. Height makes a lot of difference. Don't care for "whips", but I went from a 36"-40", to a 48". Helped a lot in receiving. My Cobra 29, has always put out good. Club always uses CBs on trails. Long hauls, I put a cheap Realistic, in my truck, for info, & convoys. Use a magnetic mount steel antenna, on the roof. Radio has been checked & peaked at a shop, antenna reeds good on SWRs, but I only get 1/2 mile or so trans/rec. Gotta be the antenna.
A good CB shop can help by "peaking " out the unit, even with out adding illegal power boosters.
I put a cb in my dd/trail rig. Comes in handy out on the trail, but also on the highway. Like stated before by someone else. I was at a dead stand still on the way home from work last week and was able to cut it on and find out why. Also even if you leave it on and listen and don't do any talking, you find out where all the troopers are sitting on the highway do you don't go flying by them. Comes in handy!
Here is my mount. Home made, but needs to be taken off and sanded and painted.
As you can see I ran my coax cable back behind my tail light and into the cab. Right now I just have the cb tucked beside my drivers seat between the seat and center console. But once I make some brackets I'm going to mount it above my mirror.