As much as I would like to complete an Ultra distance BF, it's just not going to happen with my current goals and plans. Because of some PF problems and the distances I wanted to do, combined with trail conditions, I went back to shoes. I have been barefoot running for almost 3 years, with year 2 about 95% barefoot. Just had to face the facts that I was limited being barefoot and had reached a distance plateau. Everyone is different, so I hope you have more success with your BF distances.
I currently use New Balance MT110s for most of my trail runs and I have Altra Lone Peaks for extremely rugged conditions. Unshoes sandals for shorter, less technical terrain. I had my first sandal Ultra distance of 50k two weeks ago, but it was a flat road. Rough chip seal had my soles very sensitive, I could not have gone further, but I was happy about completing a "minimal" Ultra.