You have a lot of solar for a relatively small battery bank. Based on my experience with my truck, I would recommend that you consider replacing you manual switch, which you will forget to connect or disconnect, with an automatic switch, such as this one. http://www.bluesea.com/products/7620/ML-ACR_Automatic_Charging_Relay_-_12V_DC_500A
This will have the added benefit of allowing your solar kit to charge and maintain your starter batteries. You have so much solar, why waste it?
All the best!
I am thinking about a third battery. The space the batteries are sitting in, there is just enough room for a third. The box I am building for them will be built with a third in mind just in case. Three will give me 225AH total. That should be about three days of reserve (to 50% on the batteries) during bad weather.
Thanks for the suggestion on the auto switch. After killing my first yellow top I have been pretty prudent about the boat switch with these batteries. I like the K.I.S.S. principle too. If the auto switches work good though I'm always open to improving my system.