Is it possible to use diuretics to stave off bloating?

I would say ,though it may be the opposite of what you're thinking, actually drink more water now, at first you will retain some water but after about a week that will be gone and a well hydrated body will not retain as much water overall. Also, before the wedding cut out as much salt as possible. Oh one more idea black coffee and cranberry juices are natural diuretics, try those.