1. I don't believe you can just change COL, you need to physically modify the wings.
2. COL should be directly behind (or inside of) COM
3. I've been at it for hours, and it just won't work. Your gun mount is incredibly unstable and causes the plane to wipe around in the air. Modifying the wings is a nightmare because of how you used layers of fuselage.

4. COT is on a different y- coordinate than both COL and COM. I believe it has to be at the same height to work best.

5. Adding weight to alter COM is taking your plane past the point at which you can lift it off the ground. More HP needed.

I'm sorry, but I've put too much time into this with little results. I'm not sure what you're willing to lose aesthetically speaking to gain functionality.

Why