I believe you can access many still via on foot or bike but ATV's i'm sure are a no-no.....I think the only drive in spot is via the Vail cutoff road. Doesn't open particularly early and it closes in the evenings...no camping is allowed. Get a map and you'll see the 2000 line access point. All this info subject to correction...been couple years since i've entered. Good luck!
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JD