ah i see!
I missed the bit about the physical. You may just have a problem there. If you search this board you will find plenty of suggestions on how to do the quick fix thing using a condom rather than the bottle. Obviously a condom is a lot easier to lose after use than a small bottle. All I can suggest is, if you go that route turn up at the place and tell them you are busting to pee so you can get that out of the way first...use your imagination on getting rid of the condom. There are ways of concealing it if you think hard enough and are desparate enough!