The inverter has a decent datalog display that lets us see what happened for the last 24 hours. When I ran the system with the single pack, I had a 13.5 hour period where the batteries had run out, and I needed to run on grid.
After installing the second pack, this on grid zone shortened to 7.5 hours. Looks like I could make it off grid all night if I had another 220 Ah, or I need to reduce the average load during the night.
Will look into using the hot water tank and the freezer as short term storage devices, so I can get the freezer colder than necessary during the sunny days, as well as heating the hot water to higher temp than needed to store additional energy when it is most available, and to extend my off grid time by moving those loads to when the power is available.
The midnight classics have an output for when the batteries have been fully recharged, which could enable running the bigger loads only when the solar is overproducting.