Yes, telling them about good co-ordinates, descriptions and clues should be helpful. You might also want to say that most cachers are frequent and experienced countryside users, and so are perhaps more aware of environmental issues than many of the general public. You could also point out that they themselves can access the cache pages and read current logs on them, so getting realtime feedback from visitors to their sites.
I'll add a piece to the agreement page saying that permission has run out but negotiations are continuing. Do you want me to say anything specific there?
Do not go gentle into that good night.
Rage, rage against the dying of the light. (Dylan Thomas)