I keep my traps in a "staging area". I don't want the turtle traps directly in a throw area, but in the area they travel to the feeder. They'll find it, much like the BG will find the food. It just takes a little while.
Once the turtles start getting accustomed to the location of the trap to sun themselves, be sure and check it often. I've screwed up and had it so full the trap door wouldn't even fall.
Now if I can figure out out to keep my extremely fat Tilapia out of the food, I'll be set.
Good luck, and TH is definitely the way to go.