I ended up being the only one in the shelter last night. Other hikers stayed in tents and a hammock. I was up and gone by 7:50 AM.
The heat continued. I checked the temperature and it was 90 degrees. The trail was still rocky when I stopped at the High Point Shelter for water. However, the trail north of that shelter had way fewer rocks. Hurray!
I got to the Secret Shelter at around 4:30 PM and met the owner, Jim Murray. Jim owns the Secret Shelter. He did a through hike 30 years ago and then settled down on 85 acres. His shelter has electricity, heat, drinkable water and is totally enclosed. I cleaned some of my gear with the water and just relaxed for the rest of the evening.