I think what you really want is rising and falling edge detectors. You're only concerned when the first light detector goes high, and when the first light detector goes low, and not so concerned with the state of the other light detectors. From there, you can wire them into an RS NOR latch.
Since simply wiring all the outputs of the light detectors together is equivalent to ORing them, you'll only need one rising edge detector. Have that feed into the SET input of the latch. You'll also have to feed the output of each detector into their own falling edge detector, and from there wire all of them into the RESET input of the latch.
You'll also have to isolate the outputs of the light detectors from each other leading into the rising edge detector, but that's easily accomplished using a repeater.
After tooling around in creative, there are some additional things that I noticed. First, I had to use a pulse extender on the reset input to the RS NOR latch (I used the sticky piston version). Secondly, the delays I used for the edge detectors is slightly different than what is in the wiki. As with a lot of redstone circuits where timing is important, it's usually necessary to adjust the delay on the repeaters to get everything to work properly. Finally, if combining the signals from the various light detectors before passing them through the edge detectors, you may notice that a set or reset doesn't toggle the latch. This is very unlikely in a light detector since all of them should change states before any change back.
As promised, here are some MCEdit schematics. They aren't the prettiest, but they're functional.