Voltage, current, and temperature all affect SOC. If voltage is related to battery state of charge, you have to compensate for voltage variation due to current movement through the battery not just when a battery is at rest.
That is great your setup is working for you, you understand your usage and capacity.
2012 Dodge 3500, SLT Big Horn,CC,DRW,Cummins HO, EB, 4x4, 3:73, Retrax Pro, Q20, TST507, Garmin RV760, Sleek 4g
2014 Cedar Creek, 36CKTS, 640w Solar, TriStar MPPT 60, Magnum 2000w, PI EMS, WiFi Ranger Elite, Sleek 4g, Wingard DTV Traveler
Retired Army in 1995, and now retired in 2016