Right now you’re saying about the unscrew etc it all seems unnecessarily complicated as you say.
I’d have thought just buy a little one-way-valve attached to tubing like most of us have for one-man bleeding on the fly. Cheap as chips and easy to store for if you’re stuck
Bit pointless on a car, still need a bit of tube to stop the fluid going everywhere.
@pdlouche complicating an easy system