I'm happy you found it! I totally forgot to offer specifics on how to get there (sorry). It gets a little confusing way back there, but as long as you stick to the most-traveled route, it's not too bad. I really enjoy this ride, despite the roughness of it. Can you believe I got my Subaru Forester back there once? My last time out there was with my girlfriend in mid-fall and we too, stumbled upon the carcass of the horse. It was really sad, although sort of a relief. I actually saw that horse when it was alive during the summer, a few months prior. It kept pretty close to the water crossing area as it was dragging a rear leg and horribly thin. Poor thing...I felt really bad when we first saw each other (me on the tw) and it frantically stammered to a standing position. I contemplated ending it's suffering then with my 9mm, but figured my luck, I would have been caught and turned in for killing a wild horse. I hated to arrive at the decision to let nature take it's course.
Nice work on finding it though - the petroglyphs, that is