I can't see the photos, so I'm guessing:

Hopefully you'll go many years between needing access, if ever. *Why
not frame and drywall over it? *When and if the day comes that you
need to get in there, drywall is cheap and easy. *Well, easy compared
to sliding panels, doors, false walls, or whatever else that you might
only use once in ten years.

I hear you. But with my luck it'll clog when only the wife is home,
and she'll tell the plumber the wrong place to break the wall, and oh
what a mess I imagine. I'm not happy with false wall, etc. either.
I'll keep thinking about it. But I do appreciate the ideas!