Yes, it acts as an isolator, allowing current to flow one way - TO the house batteries.

https://www.amazon.com/gp/product/B0002UHVYQ/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

This thing. So, if I am reading things right, to properly charge the house batteries from the alternator, I need a DC to DC charger. Ok!

Also, flooded cell versus other types - hard usage drops the overall capacity of the battery - even if you don't deep discharge. So there's that conversation. Man, you need to swing out west! Or I need to head east, one of the two. I think a weekend campout would lead to some excellent campfire conversations!