While there are several ways to have the panel charge the second battery bank, I question why you have the four golf carts separated into two banks?
It would seem that you'd be much better off by following current practice of combining all house batteries into a single
bank -- full time. Especially since you have a none-too-large total AH capacity (440AH) on a 37' boat.
The advantages of a single bank include:
1. each battery is drawn down less than it would be in a two-bank system, making for longer life;
can be faster, as four batteries will accept twice the amperage as two batteries; and
3, you don't have to worry about switching in each battery bank separately, or at all. It's automatic.
If you currently have a 1-2-ALL-OFF switch to select between the two banks, you could simply choose to run them full-time in the ALL position. I've done that on my boat for nearly 20 years.