I usually eat something I know runs thru me. Or, maybe you should stick to a liquid diet until you go, as you may have the beginnings of a blockage. Especially since you have had problems for 5 years. Crohn's leaves scarring which can cause partial blockages and such. Just out of curiosity, are you experiencing pain, bloating, nauseaness, and not passing gas? If so, don't hesitate to go to the er...you could have a blockage, and they aren't pretty should they rupture.
Good luck!
Donna