Ed, the Hancock townsite is pretty wide open. I can't imagine you'd have problems turning a good-sized trailer there. The road from St Elmo may be another story, though, and I'd sure want to scout up there before I'd haul a large trailer. As with most such roads, the conditions you'll encounter will depend as much on the latest set of storms and how long since the last time the minimal maintenance was done as anything. In other words, whatever things were like on my last trip, they're guaranteed to have changed since.
My wife's the horsewoman of the family, but even with my modest riding experience, I'd agree that that'd be fun country to ride in.
Scott