Even on the flats you'll notice that big trout tend to hang out near depressions, points, sandbars, oyster beds, etc. Big trout like to hang near drop-offs, close to deep water for safe haven, and in the shallows or on the drop's edge.
Quiet, stealth approach
When approached on the flats trout are very difficult to sight cast, and it's uncommon to see them before they see you; for this reason they're easier to wade fish than to approach with a boat.
Fish at night for big trout.
Big trout feed at night. There's less boat traffic at night, and less pressure from anglers. Lighted docks provide a great habitat for the big fish. If you want to consistently catch jumbo trout, fish at night.
Fish big baits for big trout.
Big trout are typically lazy. They don't want to work hard for their next meal. But it's amazing how large a bait they'll try to devour. It's not uncommon for giant trout to attack small trout while they're being reeled in. You want big trout? Fish big baits.
I really don't have the right answer for that I normally would look for a color change in the water the darker the deeper. Besides that you could probably do a reconnoissance during low tide to find the deeper depressions and drop offs. hopefully someone else has more info to better answer your question.
Not to sound like a smart ass, but a depth finder is the best way to find the dropoffs. Wading is also a good way to find the small slews between sand bars that trout, flounder and red fish like to hang out in.
I"ve had good luck at night under lights with a 1/4 ounce jig heads fitted with glow in the dark cocahoe minnows, white or light colored speck rigs ( 2 jigs in 1 sometimes catch 2 fish at once ) work good too.
