Status Report:
Yesterday I used a 40amp LifePO4 specific charger, direct from Li Time themselves and charged the batteries for around 6 hours until the charger indicated that they were at 100%. The voltage at this point was 13.7 volts, not the "14.2V to 14.6V that they are expected to be when full.
I then reset the shunt/monitor for 400AH and 100% capacity.
This morning when I checked them, they were alleged to be at 85% and 333AH remaining.
After running the furnace and fridge for 12 hours, I'd say that is pretty expected and reasonable readings.
I checked the charge controller stats which said the 165W panel on the roof (flat w/ no angle) was only putting out a measly 1.7 volts, BUT when I checked the panel directly, I said 20.1ish V so I don't know what is up with that major discrepancy
I then took one of my 185W 42V panels, propped it up around 38/40 degrees and took a reading which indeed was the rated 42-ish V. I then plugged it into the trailer and returned to the charge controller interface for stats, where it read 34.2-ish V. The monitor shows the batteries taking a good charge so I'll see what happens after the sun goes down today.
FWIW, since my 185W panels are older, they have the MC3 connectors and I only have one set of MC4 adapters. Otherwise, I would have set up two 185's in parallel just for a good start. Although I now think just starting with one of them to see how it preforms is a better idea anyway.
So that's where I'm at currently.