S Davis,
Looks like a good system.
There is no need to heat the batteries at 50 F.
Heat and cold are the enemy but Li can tolerate between -4 f to 140 f. I'd choose to shave off 14 f on both ends. i.e. 10F to 126 F.
The "cold" end is the dangerous part. Charge below that, and the batteries become expensive door stops.
The "hot" end, if exceeded does reduce cycle life.
I'm going to go out on a limb and say I think the BMS is a little bit small amperage wise. I'd be more comfortable with 300 instead of 250.
If you intend to "moochdock" and plug into 15 amp shore power, load support is a wonderful feature. I would never buy an inverter/charger without that feature.