Wake up, drink coffee, and go #2. The key to success is going #2 before you leave.
I know several guys who shot deer while they had their pants down around their ankles. I have also taken deer when I had to do #2 in the woods. Yeah, it would be better to do it before you go out hunting for several reasons, but don't think you won't see deer if you have to do it while out hunting. My only recommendation is to have your gun within arms length when you are going!