This is my CB solution that leaves no marks on the truck bed. The antenna comes with 9 feet of wiring which is just enough to go under the antenna bracket, under the truck to the rear drivers door threshold. There I drill a hole and bring it into the valley under the threshold and snake it under the carpet to the center console. The plastic tray in the lower center console is removed with 2 small screws. There is a cable attached to the rear of the plastic tray so be careful. The center section is temporarily removed with 4 18mm bolts to allow the antenna cable to route under it. The power for this antenna can be connected to the 12 volt outlet on the back side of the center console.
The side hole I mark after placing the bracket in the post hole. I drill and tap it for a 1/2 bolt 20 threads per inch. Use washers on the inside to space the bracket properly. Seal it so water does not rust the underside.

Antenna: AUMM1XX - Mirror Mount CB Antenna Kit
Item# AUMM14-B from CB world
CB: Cobra 75 WXST

Antenna Bracket

 

How tall is your antenna?

 

4 foot but you can get it as short as 2 foot or taller, the thread size is pretty standard.

 

Did you get a no ground plane antenna?

Here's info on ground plane and CB radio antennas:
What is CB Antenna Ground Plane?

 

What's not shown is the truck tool box that normally sits up front level with the side rails. That serves as a great ground plane.