Thanks again for all the help everyone! We were up there Wednesday evening (didn't make it all the way to Inspiration) and again yesterday and did. We had RZR 4 800s that are 60.5" wide and slid right through. There's actually a second gate a few miles up from the pictured gate that seemed slightly narrower (barely rubbed tires). There's also a movable cattle gate in the valley between the first canyon and the climb to Inspiration that needed to be moved and threw us off a bit, wondering if it was private access only.
Inspiration Point was as great as advertised, and some of the views of the Ogden Valley on the road up were just as spectacular!