Sticky situation you got there.....unfortunately Nebraska doesn't have A LOT of public ground and the ground that is public has tons of guys like yourself trying to hunt it, so it can get a little crowded.

If I were you I would look into Ogallala national grasslands, Red Willow WMA which is north of McCook in the SW corner of the state, Halsey National Forest, those are the ones that I've heard have good mullies....I'm in eastern NE, so I'm a whitetailer

Also take a look at this guid:
http://outdoornebraska.ne.gov/hunting/pdf/huntguide.pdf

I GOT THE ITCH!!!!!!!!!!
BPete