I didn't hear back on conditioner recs beyond Graham's so I talked with Simmons and they felt OK with using Obenauf's Heavy Duty LP. The process was nerve racking and I feel a little like I got off an actual horse because it took about 2.5 hours. Very happy with the end result though. Here are some before shots, active process and final product. I'd take another outside pic but it's currently snowing.
Before
Before
Test
Used a section of an old shirt and some elbow grease
After (I'm in love with a horse)