I am wrong. It is Nebraska National Forest. You may want to call them to see what is open as they had a fire several years ago. You can drive all over, lots of hiking trails and yes the sky is unbelievable. They have a tree nursery that they grow seedlings for all of the state.
If you have time you don't want to miss North Platte golden spike towel.
You are going straight to Valentine, not cutting across to Merritt Dam right?
By the way what are you driving?