Private room is my vote as well. I attend the public pool on occasion, and never change in the regular area, always in a seperate single room with a door. No one needs to see any adult drop his/her pants and be wearing a diaper, it should be done in private. I am sure there is a room to use for such people, or a handidapped stall even, I am sure if you are legit and have issues, they would work with you to give you somewhere to change by yourself.
So I'm not IC -- and for a while I was on a bit of a public/exhibitionist kick.
A few times I went to the gym in the morning and after my shower after the workout, I put on a diaper as my 'underwear' for the day under my clothes. It was a thin depends overnight diaper. There was no where to change in private in the facility as it was an older building -- a bathroom stall would have been the best option but it was in a much more 'public' hallway area in the locker room. (and like I said, I was kind of having an exhibitionist streak).
Anyways, so what I did was use only one of the most secluded parts of the locker room where few people ever walked. It had one of those large mirrors in the corner like in a grocery store so you could avoid running into someone when making the corner (also enabled me to monitor the room). What I would do is open the diaper with my hands in the locker; very very lightly fasten 1 tape on each side effectively making the diaper a "pullup". Then, with my shirt already on, I would get my pants ready on the floor for me to step into quickly... I would then pull the diaper up, pull my pants up quickly, then work on fastening the other tapes once my pants were up but not buttoned. This way if anyone came, I could quickly button the top and act like nothing was going on unusual.
This worked very well for the most part. No one ever saw because it was so quick. Sometimes I had to wait a while and brush my teeth and take my time -- for people to get out of the room.
One time an older guy walked into the back hall while I was changing (I think I've told this story here before) and it was SUPER awkward for both of us. He was obviously walking to his locker and he came around the corner just as I was pulling my pants up. He turned around and said "sorry"...then came back after a few minutes. Not sure what he did in between. When he came back he said "git 'er done?"...I mumbled an affirmative and ran out the door. It was terrible honestly. Pretty well cured me of foisting this part of my life on other people in public.
I go to 24 hr fitness and they have a single handicap bathroom and shower that you can lock the door. That's where I do my changing. I wear 24/7 and I know my shirt lifts up at times too and know one has ever said a thing to me. Hope this helps. Maybe they have a bathroom like that there?.