Comments/questions:
- Great sketch - I'm impressed with the artwork and clarity.
- I assume the biner goes right next to the hammock, and the webbing clips to the biner? If that's the case, why can't you just use the Spectra that's already on the HH instead of replacing it with the climbing rope? Just cut the Spectra to about 8" and tie an overhand-on-a-bight. That's what Hammock Engineer did and it seems to work fine. Blackbishop just tied the biner on w/o cutting the Spectra so he can change it back if he doesn't like it. Pics of both of their setups here.
- Unless you're tying to a metal pole or something, I don't think you'll need the extra wrap around the support. The Crazy Creek has never slipped on me, even with smooth-barked trees. That should make it easier to adjust the hammock after it's hung.
- If you're using a trucker's hitch for the round ring, I don't think you'll need the square ring. The force doesn't need to be in line with the other rope for the hitch to work correctly. Unless I'm not understanding its purpose.
- You still have two layers of webbing running between the hammock and tree. That's extra weight.
- You're tying webbing, which binds easier than cord. Would suck to have your hitch bind and have to cut the webbing. And if you're tying it anyway, what's the advantage of using webbing over cord?

You've probably seen these, but might help just for comparisons.
- Crazy Creek setup (for the wrap around the tree). Can't find a good pic of it...here's a BGT report that shows it in the tarp pics.
- Speer 4-wrap (no buckles...just for the simplicity of it)
- My homemade set using Crazy Creek's buckles (one layer of webbing between hammock and tree)
- Hammock Engineer and Blackbishop setups from Hot Springs (connecting biner to webbing)

Hope this helps!