According to MTRPA,
June 13-14 HPR: Cody WY: WY State Prone Champs. 300, 600, 900yd –NRA Match Rifle or F-Class-- Dave Ferrante
So it looks like you've got it made. You missed the match, but the range is near Cody.
There was going to be a 1000 yard match in Worland, but it looks like it was cancelled.
We just fired an 800 yard match in Butte last weekend with at least one Wyoming shooter on the line, and the MT state LR championships will be at Missoula in late September. Bit of a drive from Cody.
I seem to recall that the Denver guys did unknown distance type matches over at Guernsey that had a greater emphasis on the "tactical" side of the game.
Hope that helps.