I use to have a 7' firestick. I used it on my old `69 Catalina and on my `79 CJ7. It was killer. I really got out and could hear everything. It was rather directional on the CJ as I had it mounted on the spare tire bump stop. My best signal was across the left front fender. The Catalina made an excellent ground plane. Still, it was strongest across the front, but could do okay off the back as it was a trunk mount, then a ball mount. All good. I used a Francis Gray Ghost on my CJ7. It was a 108" fiberglass whip. It worked almost as good as the fire stick, but was much better for wheeling, as the conductor was in the core. Thus, protected from tree branches. K40's work well and the magnets are killer strong. If you can find RG8 Superflex, that is great coax for wheeling. It has a strainded conductor. Has the same properties as RG8, but only slightly large in diameter than RG58. Hard to find. But, worth it.
My favorite mobile was a Cobra 148 GTL SSB. I have an Lafayette LMS 40. I blew the finals. Killer modulation. My base is a Courier Centurian Dwight D. A totally awesome radio, especially with the D104 Mic.