The most popular amateur bands on vehicles are 2M (VHF) and 70cm (UHF). CB radio is 11 M so it's a HF frequency but just barely. Building an antenna that covers that many bands is difficult.
I have an adjustable fiberglass stick that can be adjusted for CB and 11 meter amateur radio.
It's best to go with two separate antennas. I have separate amateur radio antennas for around town and out on the trail.
I use a detachable ham radio unit.

CB & HAM Setup Suggestions?
And mount the brains under the driver's seat.

CB & HAM Setup Suggestions?
I use a trunk lip mount on the hatch for ham.

CB & HAM Setup Suggestions?
For CB I have a stud mount for a Firestick on my ShrockWorks rear bumper and a K40 magnetic mount. My tiny CB.

CB & HAM Setup Suggestions?