What I'll do for going after big cats is go out in the afternoon with a light pole and some worms so I can catch a bucket full of perch. Then I'll head out to my "honey hole" making sure I can get set up before sunset with my river rigs.
My river rigs are a couple of 7' glass rods, medium action, and I'm using bait caster reels with a "bait alarm". What that does is allow me to unlock the reel so it can free spool but when line is taken out it will make a loud clicking noise.
Flat heads in particular are a very wiley predator. They don't get big by being stupid.
And what they'll typically do is when the grab a perch, or whatever live bait your using, they won't take it compeletly into their mouths at first. They'll grab it by the head and kind of walk around with it seeing if there is a bigger mouthful to be had for not much more effort. If there is they'll spit your bait out and go after the bigger reward. If there isn't they'll stop and swallow their meal. While they're going through this process, if they feel an odd tug back on the perch they've got in their mouth they'll spit it out immediatly. That's where allowing the reel to free spool with the bait alarm on comes in handy. Even then I can't tell you how many times I've missed setting the hook on a big ole flat head. It becomes a test of nerves, waiting for the right time to set the hook.
Like "Cool Hand" Luke I'm busting rocks.
|/ \\_| ---OllllO
_( ))~-( ))-0--))