One day isn't going to make much difference if you're consistent most of the time. If you were super active that day then you probably didn't really mess up your calorie goal that much (if at all). If you stop doing all the things you love then how are making this a sustainable change? A big part of making it sustainable is learning how to incorporate the things you enjoy so you don't feel deprived and end up having a total blowout and saying "SCREW IT!" The psychological aspect of all this is usually a lot tougher than the physical. Don't make it harder than it needs to be.

So why not create a quick exercise called "Brewing Beer Like a Mother Trucker" and use the calorie count of "cleaning - heavy effort" as I'd think the two are pretty close, and then key in a few hours!

Look at it this way - your calorie count probably isn't completely accurate for the day anyways, so it won't matter if you're "guestimating" your exercise as well, and as BigDog and sjohnny said - one day doesn't really matter. If your MFP friends are gonna be D-baggy about what you eat, then give 'em something to applaud you for like a few thousand calories burnt in brewing! And believe me, as a homebrewer myself, I know exactly what you mean - it's a hefty amount of exercise!

And congrats on supporting National Homebrewing Day. My local club didn't organize anything because they're doing a big fundraiser later this summer that everyone is gearing up for, and we're also all a bit exhausted after the craft beer week two weeks ago. I did at least get a few yeast starters going for an experimental brew next weekend!