The battery isolater was present but being bypassed for some reason. Initially I thought it was bypassed because it was faulty, however, it was perfectly fine. The adapter wire to the alternator was bypassed and the alternator wire was connected to the engine battery cable down by the isolater. There was also a small black wire that was connected to the engine battery cable as well. These were all taped together. The house battery cable was still connected to the isolater - but obviously getting no power - so it was never charging while driving - only when plugged in to shore power. I found all of this out when my house battery was dead while on the road. I thought it was charging while being driven and it wasn't. Never thought to check for the green light on the panel with the engine running.
The PO of the van was obviously unaware of this as well because he replaced the alternator right before I picked the van up because the volt gauge was reading low. Nothing changed with the new alternator and he gave up trying to figure it out. I assume it was reading low because all it was doing was keeping the engine battery charged - at 12.8 volts or so - at least that is my understanding of how it operates.
Regardless, I hooked everything up the way that it was supposed to be - house, engine, exciter, and alternator - and everything worked fine. The house battery charged while driving and the volt gauge read about 14. Just returned from a 3800 mile trip and no issues!
Got lucky this time around