There use to be the pine ridge enduro but they did not run it this year. maybe next year. as for near omaha there is that one place across the border but it is kinda stupid because it requires vehicle registration and sound limitations. there is Headworks near Genoa but it is all flat sand with some tree lined trails (loup river and cannal bottom) and anyway quads infest that ride area. otherwise check east of you Iowa may have more places, but you will have to register it through the dmv or forestry service (i don't know which) I live in south central NE (near Harlan County Lake) and I farm so i have an abundance of land for rideing.