The existing Trout Brook Preserve trail comes to within sight of the bridge's North embankment. I think the kiosk should be located there (but not obstructing photography of the bridge) and include, among its information, a notice to not trespass onto the bridge itself. A couple of period "no trespassing" signs on the north end of the bridge would also be appropriate.
Moreover, since the approach trestle will also be on the north side, assuming that does not have sides and/or a walkway, that alone will discourage many trespassers. Of course, that also limits our access to the bridge if we want to give tours when it is safe to do so.