Agree with the last two posts from Robert and Jay. I would use Robert's voltages because of Jay's comment. My batteries are never at rest. They typically have a 4A load from the store/use switch in the "on" position, refrigerator on propane, water heater on propane, and two fantastic fans running. If the fantastic fans aren't running, the propane furnace is probably set at 72 degrees. Under these load conditions, I would use Robert's voltage table to determine my state of charge.
It said that determining battery state of charge is like "dancing on the head of a pin". There are just too many variables such as battery temperature, battery condition, and battery state of rest to make an accurate determination. And I don't feel a Victron 712 is going to make that determination any more accurate: https://marinehowto.com/programming-a-battery-monitor/
I'm willing to treat my $200 set of 6V golf cart batteries like propane exchange tanks and replace them when they run out of juice. So far, my Duracell 6V golf cart batteries have lasted through 140 nights of deep discharges and still test and perform as new. That's only $1.42 per night, which drops with each additional night of use. That makes my daily battery cost less than my daily cost of propane. I'm not going to let a few pennies per night cause me to be uncomfortable and start turning off things at 12.2V. I'll just go get new 6V golf cart batteries when mine die just like I do with my propane exchange tanks.
2018 GT27Q, 73 nights 12,177 miles, 600W Solar - 110kWh, PD4655L, 6V Batteries, Blue Ox, 16" tires, 2019 F250 PSD
Sold: 2017 FC25FB, 316 nights 40,150 miles, Propride, 400W Solar - 200kWh in 216 days
2013 Casita SD17 89 nights 16,200 miles