I allow my students 2 bathroom breaks per day. We use the ASL sign for bathroom. Students check out, take the pass, and I have data of who left the room.
This is editable, so you can add your class roster and alter the form to fit your classroom.
Laminate the form and post near the door. I hang a Vis-a-vis marker near the sign-out sheet, and wipe the board clear at the end of the week. Hassle-free!