John,
A clevis wuold be a bad choice, IMO. First, it does not double auto lock, it spin locks. Second, it spin locks.
Rope running on the pin could make it turn. Then you could fall to to your death, and most people don't like falling to their death.
Rob,
The electrical tape is a nice touch. By stiffening the end of the rope, it helps to "lift" the carabiner as you remove the the friction saver from the tree, making it a little easier to remove. I might even extend the tape a little bit around the biner to prevent that from sliding(turning) in the knot, making it lift out even better.