Yo can certainly experiment with antennas but for your application on a truck or a long car, adjusting directional antennas can be tricky and disappointing.
I would rather recommend to try to run a twin-lead cable (used for UHF TV) with a loop on each end, one coupled to the camera antenna, the other with the receiving antenna. The twin lead cable offers a lower loss that the free-space propagation, the only important condition is that you should mount it so that it would not lay directly on conducting (metal) surfaces. There are special mounts for it, a wire loop carrying a plastic disk into which you insert the twin lead cable.
*** luck!