The wake-ups are definitely tough. In January I started out going to bed the first couple of nights a little after 10. By the third morning I felt terrible.

Then I went to bed at 8 that night and woke up feeling awesome. The running wasn't tough (because I'd trained my butt off) - I just had not been getting as much sleep as I needed. Lesson learned, sleep will be a priority in February!
If you train well and are smart about what you eat that weekend and about staying off of your feet, you should be okay. I'm using Galloway's Dumbo Double Dare plan right now (also doing the 5K that weekend) and if it works well for September I'll be using it again for GSC + 5K.