Make it quick, and enjoy the view. That would be my advice.
Generally, washrooms will not be available while we are on tour. Some territorial parks do have outhouses, but these are generally locked during the winter and spring. If we do end up chasing clear skies, we may pass the airport (open until 1am) at some point through the night, and I'm happy to make a quick stop when this is the case, but it shouldn't be relied upon.