I found that two moderately price GC2 6VDC flood batteries gave me more amp hours of useable energy and were more forgiving when discharged a bit deeper than recommended than two similarly priced marine/RV deep cycle 12VDC flood batteries.
I'm not a heavy boondock camper but I've found my batteries, as described above, will easily keep the 10 cu/ft fridge cold along with a few low demand accessories powered for an overnight quiet time with enough remaining energy for the morning coffee.