I wonder if it's possible to hook up two of these (or two simpler units) to measure amps in vs amps out, by connecting them to your alternator switch - so one unit measures power draw when the battery is discharging, but then when the alternator is on the other unit is measuring power put back in the battery.
Was looking at an amp-hour meter today -
https://www.amazon.com/AiLi-Battery-...dp/B07CTKYFTG/ - that might better indicate what's going on; you could compare the ah in your battery before and after a trip to see what your net gain/loss was. That in conjunction with your current instrumentation would provide a better idea of what is going on. It's a bit more pricey ($39) but less than comparable meters (the Victron one is $200
), and one could always return it if it didn't work.
If only I was back home and if only my current 12V wasn't only a year old; this thread is making me want to do an alternator-equivalent delete on my car!