I am not a cb specialist, but the problem with that is you will have no ground plain back there, composite bed and looks like a bestop. Best spot is on drivers side of hood or roof.
Cam-shaft.
Its actually for my 2 meter antenna. I tried mounting it to the hood (drivers side) and and when I keyed the mic it killed my truck (engine died). I tried multiple different mounting positions for the radio itself and aslo different ways to run the wire up to the hood and every time it was the same thing, minimal tx and the truck would either bog down or die all together. I then mounted the antenna to the tailgate itself and its worked great since then. I worked with Jerry on this because I didn't like that every time I lowered my tailgate the antenna came down with it. The truck pictured is not mine, I have a SnugTop shell, I dont know if that will make a difference or not. It has been frustrating to have to go thru so many hoops just to get my 2 meter to work properly, hopefully this will fix my problem.
*edit* From the third pic, you can see that its not mounted to the composite bed, but to the metal frame that the tailgate attaches too. I will check tonight, but I'm 90% sure that it is grounded to the truck. As soon as i get my mount I will be testing it out to see how well it actually works.