It would be more complicated, but I wonder if you'd considered having a irising diaphragm opening in the done for the spike to come out of (rather than the little circular cap that slides up and eclipses some of the dome)?
I had considered an irising diaphragm but didn't like how it looked in the closed position so opted with the cap instead.
Yeah, if you don’t mind risking scratching the paint on the shuttle!
That's what the rails are for!

