If you are looking for a compact flush mount battery monitor then this product could be worth a look. New to the market late 2019 the Thunder battery monitor will suit all the normal battery types including Lithium. The head unit displays - battery capacity in Ah or mAh, battery capacity in %, time to empty based on current usage, time to full when charging, current draw out, current inwards, and wattage usage. You can program your battery capacity (from 0.1Ah to 590Ah), type and set the high and low voltage point of your battery. Comes with a 150 Amp shunt (They go on the negative side) and a 1.5 meter lead. I couldn't find an IP rating but looking at the unit I would say the face of the monitor would be splash proof...but not the back!
Check out the Thunder power products website for details or your nearest stockist. https://www.thunderauto.com.au/