Ted and I both fish a home lake that sounds pretty similar to the one your on. Large super shallow flats (3' or less) then a very steep drop to 20+. The best thing I can suggest is to try to find some sort of flat in the 12-15 fow range. Even if its only the size of say half a football field...or even smaller. If its sandy, perch will run it during the day to feed, if its weedy, the gills should be there, crappies probably on the outside of the weed bed adjacent or suspended over the deeper water.