We use Secureall near the airport. You, and anyone likely to go on site, are issued with a photo I.D. card, have to pass through gate security and sign in each time and are issued with a site car pass. Time of departure is noted. I am told that if, at the initial meeting, the owner is none too happy you do not get offered a spot. Having said all that storage sites can only be judged on results and so far we have had no cause to complain.
Why not make an appointment to meet the owner and view the place for yourself. Will cost you nothing and means you can see for yourself.