Well, I did it. I didn't remake the cabinet; I just took everything out and put it all back in differently.With the plunger in the back corner.
And I put the toilet brush smack in the middle, just in front of the drainpipe, where there is only a tiny little area anyway. But it'll be easy to get it in and out without maneuvering it up and over the stacks of toilet paper.
Then I also took the whisk broom and the kitty-little scoop out of the corner by the toilet, where they'd been sitting since our kitty passed away. I just kept looking past them, I guess. And I moved the trash can in the corner opposite (where the litter box normally went).
It's all very blank. Which is both refreshing and unsettling.
I realized my MIL keeps her plunger and brush tucked behind the toilet, but she also has a counter thing that goes over the area, and so you just don't really see them.