To "Big easy guy"
Even If I am not sure that your story is true, I don't understand really why you complain about your physical examination at school.
I agree that the presence of high school girls to give you instructions to undress and to supervise you was rather inappropriate and also that of the deputy head teacher woman who seemed to enjoy to have power on you but it was not a big deal in fact.
You were very lucky that it happened in 1980, at my school in France which was not mixed, we would have never been allowed to keep our trousers, we were all together (but boys only) always instructed to undress in group in a locker room at least into briefs and each year of school from 6 to 12 grade, at high school two times in the nude in the locker room under instruction of the Pe teacher when we were the next to be called in the exam room.
Of course we were always instructed to remove our socks and stay bare feet even if the tiled floor was cold.
So it would have been very worse than it was for you if you had been instructed (as it might have been according to me at a serious school physical examination) to undress in briefs and if all boys had to remove their trousers immediately. And it could have been worse if you had been insttructyed as it happened at some american schools (middle or high schools) to come with just a jockstrap and to undress in jockstraps... leaving your naked butts exposed to the view of everybody beinhg here including the high school girls and the deputy head teacher.
You said that the deputy head teacher who was a stern woman liked to humiliate boys but I think that if she had really wanted that, it would have been worse for you , being instructed to undress into briefs or to come in jocks and to be instructed to undress into jocks or to let you expose for a while without closed curtains during genitals or hernia exams, it was so easy for her to have power on you.
As regards boys being pants pulled down and exposed to the view of girls during "he cough and turn " test for instance, you said that it was the case the year before, so you were lucky that it changed but I don't understand why?
believe me, complaints to school authorities or parents would have not been enough in France at my time , the 60's, to obtain a change in the set up of the physical examinations if it was a school decision to proceed in that way.
The parents would have laughed about the complaints and said that it was not important and that we might do what the school authorities told us to do without making a mess about it!...
May be things were different in 1980 but I presume that this procedure was applied since a lot of years, not only for one year just before 1980, so no
valuable reason to change it in my opinion.
So be lucky to have kept your trousers and don't complain to have been bare feet and bare chest in front of girls of your age, it was nothing.