The holding edges at the corners of prodtruding parts are always a challenge, escpecially when they run into curved surfaces
How true and I think you solved that quite beautifully!
Here’s an example of what I did:
When using one of the extreme Matcaps you can see some stretching, not even a lot. But now look at the mess I made of this in Edit Mode:

I’ll be happy to take a look when you’re finished, but what you’ve got so far looks great, I can tell that from the screenshots already.