I need to replace my two 12-volt batteries. They are setup as two independent banks with a standard 1-2-both master switch. I would like to replace these with the more durable and higher amp/hr rated six volt batteries. My problem is I don't have enough space for four 6-volts. I can fit two 6-volts (225 amps) into the space now occupied by the two 12-volts (bank one). I then have only enough room for one 12-volt (130 amps) in another locker (bank two). Any ideas about mixing battery banks with different amp ratings?