Occasionally I hear about a dealer who doesn't include these things in the negotiated price. But I think that's the exception. My dealer included those things.
The 12 volt things in the unit run off the power convertor and work fine when there is no battery hooked up. However, even if you only use shore power and never boondock, you still need the battery for the breakaway cable (the trailer's emergency brakes).
Chuck D.
“Adventure is just bad planning.” - Roald Amundsen
2013 Jayco X20E Hybrid
2016 Chevy Silverado Crew Cab Z71 LTZ2
2008 GMC Sierra SLE1 Crew Cab Z71 (traded)