Wren,
Funny you mention your Labor Day fun. Same here. Voltage starting getting weird, engine running very rough, fortunately we only had to limp about five miles to the truck.
That was Monday, got home Tuesday and ordered a new voltage regulator. Took the machine to the car wash and stopped by NAPA to see if the battery tested OK. Gads, the NAPA guy found that the cable between the battery and the system had somehow slipped off the bolt when I installed a TruGel battery in March. I put it on the battery connection bolt last...Winch first, then three fused accessory wires, then the system cable. It was pinched under the other wires so well that it worked from March to September then worked its way out and phooey!!!
I put the cable on the bolt, charged the battery and voila...all is good. Sigh....
Pirate