Just thought I'd post a little update for anyone who's interested. :)
Both horses are doing really well now. They're SUPER fluffy with the thickest winter coats I've ever seen on any horse. lol. On our first trail ride way back in October, despite not having been ridden in 2 years, the horses were so well-behaved. We only had some trouble where whenever we walked in the direction of their home (of course), they would stubbornly keep trying to go in that direction. But after a few rides since then, they're absolutely fine and seem to enjoy the change of scenery. I have ridden the pony a couple times, for no more than a hour at a walk, each time listening very carefully to her to make sure she wasn't uncomfortable. However, I couldn't detect any signs of discomfort at all. She was so willing to go, and she would get so excited whenever we would reach a clear meadow (as much of the land where we ride is sparsely wooded trails). I had to be careful in the meadows because she would break out into a canter at the slightest touch of my leg, and a few times I let her go since she seemed to have so much energy. I guess that's a good sign, though, right?
Most of the time, though, I ride the Paso Fino/Rocky Mountain Horse mix named Napoleon. He is such a smooth ride and is also super well-behaved. Here is a picture of us. :)