That looks good. I wonder if the antenna mounted on the side of the box gives a ground plane that is somewhat directional i.e., to the left or right of the direction the truck is moving (if my meaning is clear). Would an NMO mount in the middle of the box (or the center of the cab roof) make a more efficient ground plane and therefor radiate in all directions?
I don't know if my question makes sense or is vague, but I hope you'll understand what I'm asking.
Then again, you seem to be hitting the repeaters and doing well on simplex too, so maybe it wouldn't make a difference.
Russell