Solar charger for 4 6v golf cart batteries LONG TERM?

It looks like an expensive unit. E:

I'd allow some fooling around time after putting it to work to make sure you and it are on the same page. The temperature compensation sending unit will have to see where the batteries are. Sometimes solar heating will heat the structure where the meter is.

I wouldn't want to see my flooded batteries lower than say 12.90 when the temperature is below freezing. You're in PA not North Dakota so absurdly low temperatures should be uncommon.