No kidding, the Turnigy wasn't designed or marketed for RV use.
The Turnigy costs between 1/10 and 1/5 of the cost of dedicated battery monitors and provides essentially the same information. I would hope you get something extra for all that extra money!
The "extra" that dedicated battery monitor gives, is the convenience of use. It can be mounted where you want it, and needs no reconnecting to go from one function to another. Costs 5 times more, yes.