I think perhaps one guard at every exit. When you check in, you get a ticket with two halves. Half goes with the trailer, and half stays with you. When leaving pulling a trailer, BOTH HALVES of the ticket must match up and be presented!!!
Also, perhaps on paperwork when checking in, list the license # of the trailer, so if there is a problem at the exit gate, the trailer can go back and be reparked and the office or security staff can contact the owner of the trailer to verify whether it should be leaving or not ...
A checks and balance system somehow...
As for dogs and other things laying around... I would not leave my stuff unattended and it is not the show staff or security responsibility to watch EVERYthing.
If you are leaving the grounds and go to lunch etc... lock your dogs, etc.... up or put them back in your hotel room, etc... for the duration you are gone. If you are going to the arena to watch, take them. IMO, if you bring them, they are your responsibility.