For what it is worth, I usually just use a regular tampon, but often ride a lot longer than the tampon is sufficient for... the pad in my shorts doubles as a maxi pad back up...and litterally: it all comes out in the wash. As crazy as this sounds, if the tampons are causing problems...just go with out. You are wearing black shorts and its not like you are risking riuning your favorite pair of Victoria Secret lacy drawers... The idea of intentinally doing nothing seems really odd to me, but how is that different than wearing a tampon for 6 hours on a day that calls for a fresh one every 2?
Another thought about the "cup" things is that a regular contraceptive diaphragm works like that too.
Karen