Vindicated! The dual inverter setup performed admirably today.
The non-essential cluster is shutdown immediately during a power outage, while the 1kW cluster is shutdown when either of the two 100Ah batteries falls under 10% SoC (~11.5V) — that’s after 26 minutes in the screenshot.
But there was enough power in all three battery banks (1x 100Ah, 2x 100Ah and 4x 26Ah) to run the essential cluster (home wifi, cameras and automation) along with fans and lights for another six and a half hours!
And yeah, we had a 7 hour power outage today. I had to switch over the load of general purpose inverter with a single 100Ah battery (it powers lights and fans) to this setup halfway through. The lights and fans are in my parent’s rooms so they were comfortable the entire time, which makes all of this worth it.