This is truly a worry of mine while out trooping. Some guys only troop in their costume for a couple hours which would be tolerable and unlikely for bathroom incidents. I'm in the process of building my Scout Trooper and my flight suit is a one-piece, but I also have a ROTJ Boba Fett costume. I only experienced one time in my 3years of cosplaying where #1 hit me pretty hard. It was at a venue where the only public restroom was at grocery store next door and you had to ask for a key! But it was an incredibly busy restroom. And NO way was my #1 gonna wait. Thank the lord it was at night and there was a park with heavy foliage across the street. Boba walked over there, took off his Cod/Kidney Armor and thankfully his one-piece flight suit was constructed with a double ended zipper, and he conducted his business there uninterrupted - thankfully. Now if that was #2 a knocking....I don't know what I woulda done.....it, it woulda been bad! (And I'm not sure that story woulda ever been told - Hahaha!)
There is a pretty good and entertaining story by George Brett who was a 3rd baseman MLB Hall of Famer for the Kansas City Royals on YouTube (Titled: The George Brett Story). The video is only 3 mins, but was so great! So.....it even happens to The Greats!
I just pray, that this doesn't EVER happen to me. I'm pretty good with gauging my consumption of liquids (with the exception of the above incident) - I once went 6 hours in my Fett costume without incident and believed myself to be adequately hydrated - the drinking to sweating it out ratio. My management was drinking 8oz of H2O w/electrolytes every hour.
I understand that this is a REAL concern for some, but with proper precautions and preparation there shouldn't be any fear. Like @Darth Voorhees stated, just handle the business before suiting up.
😉
-Iron