Here are some various thoughts that come to mind :
Moderation! Don't go crazy with the cheat meal, and you will reduce the bloating.
Post contest, you will get bloated. Its going to happen. Diuretic use will make it worse. The harder you pull water, the worse the rebound will be.
Some people are more sensitive to carbs than others. You may naturally have a greater sensitivity. Still, bloating is going to happen. After being on a calorie restriction, you are going to have heightened insulin sensitivity and increased response to food. This can be a good or a bad thing, depending on what you eat. You aren't going to store fat over night, so don't be afraid to enjoy some food but also make the most of your clean foods so that you can grow and improve for next year!