Tried approaching any of the adjacent private landowners, and seen if some of them are either sympathetic to your cause and/or the type who'd love a chance to stick a finger to the relevant authorities?
This has cross my mind multiple times. There are some beautiful residential properties overlooking some state parks. With clear 3 statue mile visibility into the park.
I’m not fond of solicitors entering my private property - I don’t feel confident knocking on doors asking for that type of permission.