Nothing less than 100% will cut it, if you really want to get stable. And I'd wager that that chocolate cake you had last night is playing a HUGE role in today's bloating. The only way to manage IBS is to do it with diet and lifestyle changes, not for a few weeks but permanently - sadly there is no magic drug that will let you safely eat anything you want, and there isn't a cure But you CAN manage it - and this diet is the best way that I've found yet.
Miracle Whip Light or Fat Free are generally ok, again in VERY SMALL amounts. Just check the fat content (of EVERYTHING!)
PS If you're looking for some discussions on gaining muscle on this diet, check out the fitness board, there are a few of us there with the same goals.