That maker and others originally used a positive earth electrical system. Modern electronics gadgets have made that very difficult as a negative earthing system is more or less essential as it becomes very difficult to isolate such gear and prevent mistakes being made. A vk1 had an early land rover which he decided to convert to negative earth and reported the huge increase in ignition noise in his 2m radio. I wondered whether Rover continued with the positive earth in later models.
A great deal of my yearly contacts are from my 4x4 truck over marginal roads and in wooded areas. I have found that if I use the 22 inch Hustler mast (the real short one) that keeps my overall whip to about 4.5 feet with coil and stinger. Less breakage at that length. On twenty it allows me to chase SOTA and POTA just fine. Not the best antenna, but it gives me contacts. GL OM John N0EVH
My solution to this problem is base loading with a flexible whip, mounted on the front bumper - less efficient, I know, but any antenna is better than a broken antenna!
I have a couple of homemade antenna bases/loading coils made by winding solid copper wire on a 50mm PVC former, one that can be tapped to cover 80 - 15m (but primarily used on 80 & 40m) and another smaller one that covers 40-10m. Both are used with a 2m stainless steel whip similar to what’s used on commercial Aussie autotuning HF antennas i.e. Barrett and Codan. Actually, the whole principle is similar to those antennas - I think it must be “convergent evolution” if that’s the term I’m thinking of. There’s LOTS of overhanging trees on the fire trails that lead to SOTA summits - and on 4WD tracks generally, round here at least.
Most of my events are in forests, and having snapped and lost a 10m/6m/2m/70cm mobile antenna I learnt the hard way. (as I didn’t use 10m & 6m much) I replaced this with a dual band 2m and 70cm.
I might have to try some more SOTA and Motorsport combinations.