What I find hides a belly very well (besides extreme corseting) is ruching across the stomach. I didn't really believe that until I started trying on bridesmaid dresses for a friend's wedding, and the ones with ruching across stomach actually did make me look slimmer. Unfortunately, that only applies to modern clothing, but it's useful to know.

Hee hee. I can't imagine any boyfriend, past or future, wearing one of my dresses so I could hem it. Though that might have more to do with my being very short than any unwillingness on their part.