Inverters need to be as close as possible, but not in the same area as flooded cell batteries. If yours are not in the passthrough and less than six feet cable length from the batteries...keystone installed wrong. If you had agm batteries, then it could be in the front and on the back wall. Inverters are still only 90-93% efficient these days, so multiply whatever is drawn on the 120vac side max current including start and icemaker by about 12 and you get the max current draw out of the batteries. And the inverter manufacturers specify orientation for mounting the inverter, so you should look at the manual and make sure it was done correctly.
2012 F350 6.7 L dually, 2013 3800RE with 6 pt leveling, Sumitomo 17.5" load range h tires, Samsung 18 cu ft residential fridge, 8k Morryde I.S. with disc brakes. Full timing since 2012.