I hope you can catch him Moe! Will you be putting Gary's food near the opening of the enclosure and then further in each night for a few nights so he gets used to it? I can't remember if you did this last time. I hope it works. Maybe bringing the other two in on the night you set the trap as you suggested might be a good idea to ensure that he is the one that gets trapped.
Please keep us updated. Hope everything goes smoothly.