Not sure, but I have heard that there are balloon ladies...people carrying balloons that you have to stay in front of. Hopefully some one that has been in danger will show up here and help.
It would be good if you could get a 10k time to help move you up a corral and that would give you some cushion. There are lots around Thanksgiving, just make sure it is chipped timed and don't get at the back of the pack. Use it as a "training/dress rehearsal". If you are doing the walk/run test it. Give it all you got, maybe it will work into your training schedule distance too.