I have a tape measurer and body fat calipers. In the morning, I use these to determine how bloated I am that day. If it's especially bad, I can tell myself that the scale is higher than it should be. It helps keep me in the mindset that I am still in control.
The good news is that even though the fluctuations will always happen, your real weight will continue to drop. I prefer to look at things over the long term rather than a few days, because that's where you see the real trend.
And yep, even those lucky folks without IBS to contend with still see these fluctuations. Bodies are funny things.