question on interpreting MPPT controller display

Batteries are a consumable item. They are not that expensive per year over say 5 years. No way spend thousands to make the batteries last a couple years longer than they would last otherwise. Save peanuts a month. Phooey, just get new batteries as needed.

You can just recharge two at a time with the gear you have now, no sweat. 415AH x 20 = 83 amps. The Honda 2000 can do that on a power-factor corrected charger. You don't have to do all four at the same time.