Sounds like a fun day! Err, not really. Bull Gap is a great place to meet lots and lots of quad riders, seems like that's what 90% of the people there are on. I never much liked that area on a bike, there are much more fun areas to ride around there.
As for the flywheel nut thing, I had the same problem a few months back, it sucked! Mine came all the way off and then the key in the flywheel broke. Put a sliver of it back in upside down so it held alignment, but then only had needle nose plies to reach in to tighten the nut. Made it about 1/2 mile closer to the parking area before it came off again. Then had a terrifiying ride on the back of an XR400. Then had to drag the trailer behind the Jeep down a wash that was about 1/2 as wide as I needed it to be. Some spots it was close to 3 feet wide and 3 feet deep, with no option but to put 2 tires in and 2 out. Bent up the lower portions of my Haulmark pretty bad, but made it in and back out. A little hammer work later and it's good as new. Or at lease good enough for who it's for.