(and I doubt I'd do it either), is exposed screws(oval head SS?). Then you could nicely varnish the fiddles on a bench until the coating stage was complete. Not unheard of, the fiddles in my boats head were done that way. In some places it looks right and makes future maintenance easy.

I'd do what you're contemplating and tape them off for the final coats. That would probably be several if you want the bungs and fiddles to stay well coated and protected for a decade or two. And the work will pay off in how nice they look when you're finished.

But you know that. BTW, the work and new tops look great! Crying out for those gleaming fiddles.