I use an old 5 gallon pail for a blowoff container, keeps me from having to babysit. Mine (when I do hefes in a 6.5 gallong carboy) blows off even at 64-66F. Like Yuri said, the temp is going to effect the flavor a lot, and the blowoff not-so-much...
Good luck, though, I hope you have a tasty...