IMO, you are WAY overthinking this...Just take off whatever you want to wears. We have worn our clothes right off the bus to the pool. On full days at the resort, my wife picks out her bikini to be worn out to the nude area, just for the photo op for home. Other days a wrap from the room to the AN area.
No one will watch you disrobe, so no need to go to the bathroom. You will feel more comfortable once you take it off...because you will blend in with the crowd.
We both remember our apprehension...now we laugh about it. We have traveled to AN resorts with friends from home...and a few drinks and meeting everyone else we already knew who were heading to the AN areas made the transition...or first "bare it all" experience...an easy thing.
"Once you go, you know!" is our motto.
2012: Apr 22-29 Couples Tower Isle; Jul 21-28 HBR
PAST TRIPS:CouplesOR-Feb '95, Jun '97, Jan '00,01
HedoIII-Jul '03,04,05 GLB-Jul 06,07,08,09 Starfish-Jun 07,08
Rose Hall-Jun '08,09 GLN-Jun '09 Breezes Rio Bueno-Feb '10
Dreams RC & PA-Jun '10 Now Jade-Apr '11 El Dorado/HBR-Jul '10,'11