I didn't have to take PE - at my HHS, student athletes could get an exemption from the requirement - but that was how our locker rooms were set up too. The gym teacher's/coaches' office opened off of the locker room and had a window between the two spaces, but the "view" was only of the first row of lockers, not the shower room or the other rows.
It is a Catholic school, but we don't require our staff to be practicing Catholics even when they're direct-hire and we contract a lot of services (food service, busing, "specials" teachers, special ed) from our local public district, so for those positions it is the public school rules that apply which brings in even more diversity. Our parish is a pretty accepting one, as Catholic churches go, and the kids are all very familiar with a community/parish member and frequent school volunteer who is openly gay and sometimes attends mass with his partner - in fact, he knows most of them by name when they go into his business (the neighborhood ice cream shop)
I did get a short update this morning when I went in to update my background check info. Apparently the complaint did come from the family I suspected, and it did have to do with things their older kids (who go to the same public high school as my volunteer) had relayed. But when they spoke with a teacher and the principal, they framed their concerns about it being "confusing" for the kids because most of them knew this volunteer as female before he came out. Fortunately, the principal doesn't seem inclined to let that concern get in the way of the season - she said she offered the family advice on how to guide their children in navigating any confusion, and pointed out that our mission statement first and foremost stresses a spirit of love and service to one another. Which had me breathing a big sigh of relief, because when my co-coach and I first heard that a parent had complained about our volunteer there was a moment of "*** did I get myself into this time?!" going through my head.