Here is a bit of advice from an experience that happened to me from a now disbanded FT club in Texas...I had/have unlimited access to about 500+ acres just south of Austin, lots of water, big grazing fields, no snakes (poisonous ones) and one heck of a duck hunting place..it belonged to a long time friend of the family. I hosted a training day for my pals and basically we had a picnic trial since it was big enough to run multiple set ups..
Well about a week later,I get a call from the owner wanting to know what all the dog trucks are doing at the farm...seems like my new found pals thought the place was now the new club grounds and it was share and share alike or what was mine was also theirs..it cost me lots of groveling, dispersed among apologies, and having to replace all the locks on the various entrances to the property...
Moral to the story: be the first to let everyone in the property and be the last to leave, never give out the gate combo, and make people aware it was a one time deal...there were even a couple of people that tried to approach the owner and lease the place out from under me
I have since learned who I can bring to train to that area;-)