I wrote a response that got lost due to the 50 charachter title limit, oh well, here is most of it:
I have several similar strings hooked up on a 48V system. Hook them 4 panels in series, you will end up with two strings. On mine, each string is run to a combiner box, and there is a fuse and a diode for each string. The diode is a common 8 amp stud silicon diode with about a .54V forward voltage drop. The voltage drop is of little consequence at this voltage, as the open circuit voltage of the strings is generally above 65V at any time there is appreciable current. If I recall correctly the NEC now requires appropriately rated overcurrent protection for each string, and definitely requires a charge controller for all systems, should that be of concern to you. I believe that it was SparWeb, Steven Fahey, who posted a link to the current NEC guidelines not too terribly long ago, and I printed it out and remember that it was worth reading.
I doubt that you will cook your batteries with just the 8 panels and the batteries that you have, however I suspect that all approved charge controllers also prevent current from discharging into the panels. If it were me I would probably E-bay your 12/24V controller and obtain a C40 or similar charger that can handle 48V banks at the current you have.
Also, the bottleneck for the current for each string will be the panel that can handle the least current. If you measure the current of each panel into a 12V battery under similar lighting conditions, you should be able to get more current into your batteries overall if you put the four highest current panels in one string, and the four lowest current panels into the other. This is of course providing that both strings can reach the charging voltage. Rich