I appreciate your input. I'm happy for you that the standard minnow trap captures your crayfish. Mine must be very wary or something. I've tried, bread, dogfood, bacon scraps, raw chicken and cuttings from chicken trimmings, corn, and fish carcasses. I've been advised that the rubberized coating on the metal may be the issue. I've burned my coating off (easy to do with a hand held butane torch or in a campfire) and painted. Tried brown, grey, natural rust color, doesn't seem to matter. Tried other mesh traps, pyramid traps, not much success.
I've watched youtube videos of how viciously the innocent looking turtles can go after crayfish. Perhaps my turtles are putting a hurt on the crayfish?
I think it has to do with total numbers. Perhaps if you have 1,000,000 crayfish and can catch 1000 in a week that makes sense. Maybe I don't have as many crayfish as I think. What type are your crayfish, maybe they are more aggressive or more hungry? Are they red swamp crayfish?
You've thought about the SMB and have good reason to not put them in. I would agree with your logic.
It will be neat to see how things go for your forage in the future. Sounds like you could set up a bait shop for both the GSH and the crayfish!