DaveP, before waltzing off and trying to ask someone in the highest offices somewhere, if you can "get permission" to metal detect these, have you first seen if there is any prohibition against it? I mean, because, if it's not specifically prohibited, why would you think you need to go ask some deskbound bureaucrat? I think that's sort of like driving, and approaching an intersection that has no sign prohibiting U-turns, and wondering "gee, I wonder if I can make a U-turn here? I better go ask the traffic division people". On the contrary, if I see no sign forbidding U-turns, then I assume it's not forbidden.
You say yourself that low-level secretaries often hand an arbitrary "no" (even if no such rule exists), so why would you think that some state-capitol big shot is going to be any different? If anything, you're going to get even MORE no's, the further up the ladder you go (when quite frankly, they probably could care less, and are merely "addressing your pressing question"). And to say you're going to get it from the in WRITING, is the FASTEST way to get a no. That would seem only further imply that your activity is somehow dangerous, or inherently evil, that you had to get some sort of contract or written agreement, etc... And with that implication in mind, you're certainly going to dictate your own answer even more.
I think you just need to go at off-hours, when supervisors with binoculars aren't being busy-bodies. And you say two workers approached you, at his behest? Heck, what did you do, go at the highest visibility work-day they had going on there? Why not go on days when that rest stop is not being maintained (and hence, no busy bodies to make some stretched assumptions). And if you were still, even at low-traffic hours, questioned, well by golly, you're still looking for that ring. And if it's at another stop up the road, and they make note that you gave that same answer the week before, well by golly, your friend was drunk when she lost it, and can't remember which stop she lost it at, right?
But seriously now, if you start going up the chain of command seeking sanctions, and getting "no's" where perhaps no one cared before, and then fighting those "no's", you may just end up getting rules written, where none existed before, "to address your pressing issue". Please reconsider your plans.
