DC power issues- any advice?

I know this is not suitable for you as you say you are isolated. But when you return to civilization, take a run by the hardware store and purchase a pair of plastic lamp bases for household screw-in light bulbs.

Next, head for a NAPA store. Purchase (2) 100-watt TWELVE VOLT light bulbs. You are going to GANG the two lamp fixtures together (parallel), then lead a pair of 14 gauge wires to use as test probes. The diameter of the conductor of 14 gauge is good size. You need to STRIP a half inch of insulation from the end opposite you connected to the lamp base. Then solder over the kitchen stove burner with Radio Shack solder. This makes the stripped copper wire ends stout.

The two bulb bases need to be ganged. Run a SPUR wire from the primary base you connected the two test lead wires to. The SPUR connects to the 2nd base. It connects the 2nd bulb in parallel.

Make the test leads just long enough to be comfortable. So you won't be yanking the bulb bases around when you move the probes from place to place.

Next, go grab your jumper cables. One of the two clips is going to be clamped to a proven ground. A good negative somewhere. No sense in making the lamp tester test leads so long that they snarl.

Clamp one jumper cable to a good ground. Good grounds are not easy to find. You may have to run the cables out of the entry door and clip them to a scraped shiny piece of steel hooked to the chassis. Whatever works.

Why this and not a simple test light?

Well, you're going to clip the loose end of the battery jumper cable to one (doesn't matter which) test lead. Now that test lead is grounded.

Let's go to work.

The loose (unconnected) test lead end now can create a SEVENTEEN AMP LOAD when you touch the tip to any 12 volt live surface. The positive connection of any device, buss bar, fuse, you name it. If it has power, when you touch it with that test lead, you create a 17 amp load, and those two light bulbs can be seen for a half mile at night. A rude load test with unmistakeable signal.

If you touch something and the lights do not come on, or there is a spark, then the lights flash on then off, you have a BAD connection somewhere.

AND BECAUSE OF THE 17 AMP LOAD when you touch anything, good or bad, the test lead tip WILL MAKE AN ARC. This is good. Jab the test lead tip rather than drag it across a connection.

This cheap to make (and easy) tester has found I would have to guess, more than a thousand bad, and almost bad connections, over the years. It is phenomenal.

BUT BUT BUT BUT BUT BUT

Do not check tiny wires DOWNSTREAM of a fuse or breaker rated less than 20 amps with this critter. It'll blow the fuse. This tester is for primary feeder and branch circuits.

When you're done, unscrew the bulbs and put both of them somewhere safe. The PLASTIC lamp bases you bought are hard to break.

And yes, your eyes do not deceive. If you "test" a circuit and the bulbs glow dim in some spots but not in others, Houston You Got's A Problem.

LOAD TESTING is the only way to really test a circuit. I've seen it all with my own tester: Bright lights that grow dim or go out after a few seconds. This critter finds problems, the problems do not find you (at a campsite). New rigs, old rigs, the tester is B.S. proof.

"But that has never given me a problem" some owners complain after I found a problem while testing everything.

Then I uncover a burned or loose connection. "Wow!" the owner would say "That was ready to fail!"

Total cost? Under 20 dollars. You supply the jumper cables, or make up your own ground wire extension. Use a savage grade crocodile clip to connect to the frame.

Good hunting. This is preventative maintenance. If you don't go through your rig and test all higher power circuits, don't worry. The problem will show up sooner or later and you sure will "know it" when it does. This isn't a Pie In The Sky type of test.

The number of bad connections you will find before they find you is shocking.