Chassis battery disconnect failed while driving

You would have to look at the wiring diagram for your coach to see where the disconnect is located in relation to the alternator feed, feed to ignition-controlled breakers, etc. Not sure there is a "one answer fits all".

If you have the least concern about it, remove any solenoid-controlled disconnect and install a simple marine ON-OFF switch. Most are rated for 360 amps continuous and are just a little over $20. Totally mechanical and designed for the harsh marine environment.