Today's 3pm check:

The car has been resting for about 24 hours. It was really cloudy yesterday, but sunny today.

When I left it yesterday, voltage was 12.5. Today it was at 12.9.

After a start, it was down to 12.7.

With the engine off and the AC fan running for a minute or two, voltage went down to 12.5. Recovered to 12.7 with the fan off.

I then restarted the engine 4 more times. After that, voltage was a stable 12.5.

So, the battery is plenty health and can handle multiple back-to-back restarts even with no alternator or solar charging in-between. Seems like that should work pretty well for daily driving.

And, as we already knew, the solar charger is definitely putting some amps into the battery.

I'll try to remember to update this thread maybe in a few weeks or months after I've played with this setup for a while.