In front of the screen would be great - look at the screen, and walk back, until you can see it fully. This would be the place to search, since kid's and teenagers go there.
Usually they had a kiosk - find the place, coins was lost there, and there should be trails down to the cars, and the place where the kids like to hang out.
look for old maps airial photos, to see if you can find the trails, where ppl had to walk to get from their car to the store. anything lost on a muddy road will disappear forever. - That is until you drop by.
do you remember where ppl. stops to buy their ticket? - that can be a good place too.
If you mark your finds on an airial photo, or with a GPS, then you will soon be able to find out exactly where ppl liked to go when they wanted to deposit something for you to find.
Maybe the owner has a photo hanging on the wall of the place taken during a movie - it could give you a lot of information. make a snapshot with your cellphone camera for later reference.
Try googling the name of the place, and then click on pictures in the left side of the screen. Maybe somebody has put some pics on the net.
/Steffen