Got me some newer Mopar to drag behind the coach.

Sounds like you scored on your RV coming with the towing gear. No disagreement from me on the brakes!
Miata curb weight 2100 lbs, Xcursion weight almost 11k lbs., obviously can't tell it's back there. I'm guessing your Dart is a little over 3k lbs. and mountain driving would make brakes a no brainer.