First off, I'd found smoke and mirrors around this odd topic yrs ago.
The DRVs are generally supplied with Morryde IS can be equipped with Kodiak hydraulic disk brakes. (EoH) Electric over Hydraulic Brake Controllers (HBC) can be manufactured by several companies for a variety of applications. Our DRV was supplied with a Hydrastar 1600 HBC.
This model required a HBC-
CAM (Controller Adapter Module). This rather simple add-on allowing the trailer equipment to give the proper "feedback" to the (in our case) GM IBC. It has worked flawlessly. DRV did know about these issues surrounding some models & compatibility issues at the time, and supplied our CAM. It is mounted next to the HBC. Depending on your particular application this may be an option.
https://www.hydrastarusa.com/product...dapter-module/
https://www.easternmarine.com/ford-c...uators-4845900
https://www.etrailer.com/Accessories...r/HBA-CAM.html
Like you, having extended experience in a past tech life "flashing proms", etc. is great when you have the resources available, But. If the FOMOCO dealership is not equipped or knowledgeable enough? Plus their shop labor rates? Well you could be up a proverbial dooky creek.
FWIW, best of luck.