I'm no help electrically. If it goes beyond a '65 Ford PU wiring, I'm lost. I fuss with electrical problems for weeks and finally have to spend to get it fixed, but even then I learn something.
I'm still hoping some of the others will lend their electrical expertise. While you're waiting I'd suggest reading other current electrical issue threads and get to know who the electrical minded people are.
Electrical, Charging and Solar - School Bus Conversion Resources
This link looks like mainly solar information but you might find something in there. Have you tried Youtube yet?