Update part 2:
Friend went to the dawn wedding. She was actually quite complimentary about it, saying it was for the most part wonderfully sweet and romantic, with a few sporadic moments of inadvertant guest torture (including no actual chairs at the wedding, but rather having the guests seated on bales of scratchy hay, in their short party dresses, which must have been fun
). The only real downside to it was apparently her partner having to be up for a flight that took off at argh-o'clock the next morning, but the formal "last dance" was only held at 9pm, before their long drive back (I guess they were too polite to leave early).