Like you said, they are on top of the divide between Robert lee and Water Valley. I've been there 12 years now and have seen them more and more.
I've seen Axis up hwy 277 going towards Abilene around Tennyson and Orient Rd. Talked with a guy that gets to hunt on the Goodyear test grounds and they have some there. I've also seen some on the high spot between Water Valley and Robert Lee.