Hobby Racer,
I love you plumbing.
Great job, keep up the good work.

To make my cooling system self bleeding. I have 2 small hoses coming back to the expansion tank.
1. From the high point off the engine, same as you. I put a pill in that hose with 1/8" hole in it. This allows air through quickly but limits much fluid going through.

2. Small Hose from top of radiator, kept as high as possible, back to the expansion tank.

I teed these 2 hoses together before attaching to expansion tank.

Bob