My best luck for flat heads has been in the rivers in creeks but with open water nearby with some flats. If you can locate a creek bed with something to tie off to, run a trot line parallel right down the middle of it. If there is nothing to tie to, then anchor your jugs to help keep the jugs in the zone. Black perch has always been a go to bait for me, but success with tree frogs, crayfish, is doable. Good luck and report back on your trip!