DiploStrat- You are correct- most everyone that commented is correct. I would be happy doing most of any of the above. And I do have some experience with charging batteries- went from the East Coast of the US to S. America and then onto New Zealand with a sailing cat that I had placed 6 x 140 watt panels and 2 x MPPT's with 4 gauge tinned marine style wire (run was pretty long), Onan 5.5 KW, and alternator charging when what little we motored. But, there I had a big area to work with and simple things like shunts, fuses, isolators and most importantly a fully programable pro-remote from Blue Sky Energy made it an almost set and forget system. I really only had to water the batteries and I had a watering system set up for that. Nothing complicated.
But a 2015 Fuso FG is a whole lot different. And so far, no one with a 2012+ (as of last I saw) has responded with what has actually worked for them. According to FUSO US corporate NJ, three fuso dealers, it could be possible, but they have no experience, no testing and a strong caution about warranty issues.
I don't have Pugslyyy's room in the engine compartment. On a positive note I have found a guy in Florida that can turn a N-type alternator into a P-type alternator. So if I can figure out how the ECU determines what is worth shutting down for and what is not- I may now have a easy Balmar solution- almost plug and play.
Cheers
I got a message from Michelle at Earth Cruiser to call back mid-week. ATW I haven't tried.