Damn I hate the landowner screwed you & your son at the 11th hour.
but at least you are in THE greatest lope area on the planet!
I hunted lopes & mulies in '04 on a ranch south of Buffalo in the Crazy Woman Creek area. From the time we left the airport in Sheridan (its high fenced to keep the lopes & deer out. We saw great bucks lying beside the fences as we landed!) to our drive to Buffalo & again between Buffalo & the ranch, the lopes were ALWAYS visible from the highway & county roads. Sorry, I can't point you in exact areas but I know there were a few guys out there around the ranch roads driving through on their way after lopes on nearby BLM tracts.
http://www.blm.gov/wy/st/en.html
http://www.blm.gov/wy/st/en/resource...huntareas.html
You're in 10? I think we hunted on a 100k acre ranch in the bordering area 22.
http://www.blm.gov/pgdata/etc/medial...ge.-1.-1.1.gif
First call I'd make is the warden in Buffalo. Jim Seeman 307-684-5223
http://www.wyominggamewardens.com/map.asp
The state walk-in areas don't appear to offer anything in unit 10.
http://wgfd.wyo.gov/plpwhmprogram/up...age%20%201.pdf
Here's a list of the public access areas:
http://wgfd.wyo.gov/accessto/access.asp
Like i said, Id be calling the warden in Buffalo first. Wish I had more for you. Good luck & bless y'all. I hope you can get that boy a lope!