The tribe that needs to get on board with a GP style event would be Morongo, they have some cool areas for them, access friendly, and the tribe isnt hostile to outsiders.
I have heard simmering rumors of AMA D-37 GPs adding a UTV class for their GP series, but nothing concrete.
They do events at Glen Helen, Pala, The Ranch, Ridgecrest, Gorman, 29 Palms and Taft.
Might not happen in 2013 season but its comming.
Well I have some bad news to report. Soboba 2013 is not going to happen. I spoke with the organizers today and they are going to try for 2014. I will keep everyone up to date if something changes.
Now you're talking!!!