Trash panda update: Didn't set any more boobytraps. Sprinkled cayenne pepper powder along a bunch of their travel routes (but not fully ringing the yard) which didn't seem to do a whole lot. Maybe they just walked around it, or I need to use more? I'll try doing the entire fence line tonight and see if it's more effective if I make sure not to leave any gaps.
I tried the nerf gun for what I think will probably be the last time. Shot at one of them and the cheeky bugger picked up the dart from the grass and *ate it in front of me* (well ok, shredded with teeth and claws, but I doubt it tasted good). It's clearly not working to chase them off.
The squirt gun had slightly better success, at least a few times I did actually get them to run away after engaging.