Sounds like everything has been covered.
Toilet lid down. Close drains.
Check for and cover/secure any holes in walls, cracks under and over door, and depending on heating, I had baseboard so I had to cover it with fleece.
Remove any razors, soap, and object that can get knocked or pulled down that could cause injury or even just a big mess to clean up, lol.
Wipe surfaces of any human grooming residue.
For lighting, a night light or lighting with colored bulbs. I took an old Bathroom Dixie Cup dispenser we weren't using and took out the springs, then tucked small strand of LED colored Christmas lights inside. LED I believe do not get as hot, and the opaque of the Dixie Cup holder (white, long rectangle) diffused the light really well. It didn't look too bad either and I could see where my babies were at all times. Avoid bright lighting.
I loved using the bathroom for out of cage play. When I had my own place, I had it set up in a flash. They had more space and things to explore and could climbed to heights not possible in the tent and glide to me. They had such a blast whether I took toys in (sometimes I didn't) or not because there was so much to do, climb, jump from or glide from. They were super active and didn't get bored and bite my ears (cough, cough, Ollie, cough) like what happens during tent time. Unfortunately I cannot and have not been able to use a bathroom for their out of cage time and am limited to the limitations of a play tent. Although, it's not that bad, just more awkward for me and less of everything for them, but hey, at least they're out of the cage and can roam free on and around me, and that's what's it all about.
Make a checklist, prepare and enjoy!