EDM, "Open Fields" has NOTHING to do with REQUIRING those enrolled in CRP to allow access to anyone and everyone. "Open Fields" is basically a federal program under which the Feds kick back money to all states which have similar programs. In other words, on top of what you get from Uncle Sam, the state (of either WI or IL, depending on which side of the line you farm) would approach you with an offer to essentially lease the hunting rights on your CRP acres. For which you would receive additional state dollars, on top of your CRP payment. But it is a strictly VOLUNTARY program where the landowner is concerned, like SD's "Walk-in Areas", ND's PLOTS, NE's CRP-MAP, etc. Nobody's holding a gun to your head to force you to open your ground to public access. Just offering you some additional $ to do so, in case you might be interested.
Here's one PF member who'd be strongly OPPOSED to any program which requires landowners to open their CRP acres to public access.