Get rid of the woven ground strap (if yours came with one) and run the battery ground cable directly to the starter then, if you are using a pan (vs. a tube chassis) and still use the woven strap (or replace it with something that holds up better) for body ground. American cars used the woven straps for ground back pre-WWII and a few years later before they went to the twisted style of cable used now days. Also, there were some cars that were wired positive ground vs. wiring using a negative ground like they do now days. I think there might be one Mfg., as I understand it, that sill uses the positive ground method. The flat straps have a tendency to have the strands corrode or vibrate enough to cause the strands to break apart, usually at the hard clamps used for the bolt connections at either end of the strap.
DC, as I understand it, has the working load on the ground side of the circuit (one of the reasons you disconnect the ground strap/cable off the battery before the positive strap/cable off the positive side of the battery. AC works differently so it switched differently. If you are going to put a safety disconnect switch in I recommend using the ground as the shut-off portion of the circuit (works good for anti-theft as you can hide it and is best when storing your "toy" for long periods of time without having to pull the ground cable off).
https://community.cartalk.com/t/positiv ... em/40353/7
http://www.answers.com/Q/What_is_the_re ... und_system
https://www.bpnorthwest.com/voltage-sta ... round.html
Something else to consider is that as metal fatigues (with age) the chassis ground decreases in its abilities to work as a grounding platform. Add to that if things have been modified by someone else: were the welds cleaned well before welding? Even in new modern cars now days it is my understanding that they are still having a lot of problems that end up being traced back to ground issues. This is why, for off-roading (I run in the sand) that I bypass the chassis/pan as primary ground and use a ground cable directly to the engine's starter then a cable to the chassis as ground from there. I might be running in rougher areas than you do but it is something to think about.
2) If you are going to play off-road then I would also put a circuit breaker in the line going from the Alt to the ignition as protection as VW never did use one for protection. (this sentence is on the extreme end of wiring and more for single use rough housing) When I wire for the sand I simplify the wiring and break the circuits up as individual circuits so in case one circuit, other than the run circuit, goes bad on me I can get back to camp, not be stranded out in the boonies. If you are dual purpose then this breaking up of the circuits might not work for you but it has for me.
I use heat reset circuit breakers, matched to the circuits draw, instead of fuses; there are manual reset types also. I run two main circuit styles being switched and no-switched/hot circuits for several reasons one of which is when you get back to camp and start tippling to the point of "getting stupid" so that your radio (a CB in this case) does not keep everyone awake all night because you forgot to turn the key off
(geeze, had this happen to our camping neighbors many times!). There are times when you do want an non-switched circuit and that depends on what it is and why.3) For off-roading I am thinking more and more about moving the traditional "everything from under the dash" to the rear of the car (shorter electrical runs) and only run the off/on start, and wiring to the gauges forward (also adding a second starter button for "bumping the engine" but w/o a "run wire" to the ignition. A smaller wire bundle (hopefully) and easier to get to. May not work well if the rear seat is being used but then the cage often makes this impossible to sit people in or work on the electronics... which is why the long running debate with myself.
I hope this helps someone.