The sun was setting, and we were out of luck for camping in the park. Camping in Yellowstone was also not in the cards - the legal campgrounds were full, and we just aren't squatters - not with a big, white, obvious trailer behind us. So, we pushed on through the night and saw only black skies and an occasional cloud of steam through Yellowstone. Oh well - another 'gotta go back and do that one'...