another ham (KD7LFO) here, I've seen some pretty beefy bumper mounts on military communications vans. On the wife's truck, I used a custom diy mount that fit under the hood at the back corner on the drivers side (she more than once threatened me with bodily harm if I punched a hole anywhere on the body).check Ham Radio Outlet or MFJ enterprises for ideas.
Jim, I bow :bowdown: to your experience in the field --- I do have an old CB license (KIP 6970) from the 70's