Suggestion: Cosplay workstation/repair room
It would just be a room with a few tables/ chairs/ mirrors with available sockets for hot glue guns/ etc. It would be up to the cosplayer to bring all supplies. The washroom layouts for the TCC and Doubletree pretty much seem to be, a small outer room (for the TCC a corner like area) and the main washrooms themselves. Especially for Saturday, the TCC and Doubletree washrooms had cosplayers practically filling up the entire outer room with cosplay supplies either doing last minute sewing or repairs.
I don't know about others but when wearing bulky costumes (ie hoop skirts) I like to remove them in the outer room temporarily so I can use the washroom stalls. There was no room for this with all the cosplay supplies set up everywhere.
Anime North 2013:
Friday - Akashi Seijuurou
Saturday/Sunday - Melty Granite