Bob, any update from your tech buddy?
A was looking through a service parts list that Spartan sends out to all new chassis owners. I see an item #S-1628-001 on there called "Tow Vehicle Brake-Aux Air Kit" for a price of $365.33. That sounds like the part needed to sanction installation of this AF-1 system on their chassis.
2014 Newmar Essex 4544
2007 Lexus LX470 Toad