I rode him for 3/4's of our time out in the woods, and walked him about 1/4th to practice really steep, loose rock hills. He went down medium hills, loose rocks, with me riding him, very well yesterday, and didn't get nervous when he started to slide down a bit. He just went with it. But there was another, very long, steep hill that I thought it was better to practice on without a rider first. (I got some very good exercise walking up and down it. I'll refer to it as Heart Attack Hill.) Heart Attack Hill will be a very good hill to work Tweed up and down when he wants to run back to the trailer.
During the walking portion of our adventure we ran into a deer, and I let him stalk it through the brush just so he knows he is the boss when it comes to deer. When I remounted, we came across some rental horses in a pen. They didn't do anything, but Tweed went on high alert, so I dismounted and worked him around them. He never fully relaxed, so we will going back there the next time down.
Back at the arena I made a new friend. She was there all day with her two horses for the first time, and she moved her trailer over by mine. She was really sweet.