Mike Collins and I summited Sheep Mountain via the shortest legal approach. It was approximately 40 miles RT with ~8000' cumulative gain. The trail system is in great condition, and the mountain provides an awesome viewpoint. Highly recommended.
SIDE-NOTE: During the past few years, there have been multiple border patrol and drone incidents in the border area north of Sheep Mountain. The illegal border-hopping approach that some people have taken in the past is not recommended. (Plus, you miss out on great trail hiking and scenery.)
I did this hike in about 4 hours. So I must be really really fast since it is like 54 miles round-trip from the closest American trailhead. Uh, I guess that would be like back to back two hour marathons on trail with ups and downs. Fast I said, lightning fast! Or something like that.