Battery monitor question

Piano and BFL, thank you both for your thoughts. I do remember reading the Puekert and amp hour draw "wars". My uses are always small, my only large draw might be a coffee maker, but I like percolated coffee much better, so I don't see anything more than led lights and a tv, and the furnace in colder weather.

I am still leaning towards the Trimetric system, but I haven't bought it yet.
My in my old 27-5L, I used a simple amp hour counter from ebay, and monitored things myself. I have decided to use something better in this new camper.