I would not hesitate to ask a rank-&-file hired worker hand. In my opinion, they do indeed, if-so-subrogated, have the ability to say "yes". Oh sure, their superiors can "over-ride" that. Fine. For example: if you walk into the supermarket, and ask a cashier "can I use your restroom", that worker might point the way to their restroom, right? BUT WAIT, that cashier is only a hired-hand-worker. Perhaps you need to ask the store manager, right? BUT WAIT, even that store-manager is only a hired-hand, by some coorporation from elsewhere, right? So you need to keep going to the top, to ask the person who actually holds the pink slip to the store? Nah, in my opinion, the lowly cashier can grant ok's for such things. Now later on, if his manager scolds him and says "but that's for employee use only, and we don't have public restrooms", that's between that manager and the cashier. You are not in any trouble.
Thus I have gotten permission from field workers who don't even speak english, to hunt an orchard of a field (when its very clear they're just hired hand field workers). Or from workers on a demolition site, when ... in fact .... they may just be a hired subcontractor from whomever hired them to tear down a building.
If they say "I don't have that authority, you have to go ask so & so", then fine. So be it. But if they say "yes", I'm not going to argue with that