Can't remember the bosses name, but in the early  60's, I worked for Butler Amusement in CA; and for a short period, we had the "Zanilla the Gorilla" sideshow; and a couple of times for a day or two, I worked for him.
 
The show was in an old beer truck, with a tent on one side.  We had a door with bars across the hall in the middle of the truck, and in the back of the hall was a transparent mirror at an angle, that would slide "FAST".  The mirror was shut at first and in a side panel was a beautiful girl; with bright lights on her.  It looked like she was in the back of the hall.  Behind the mirror was a friend of mine (forgot his name now) in a gorilla costume.  The lights would slowly dim on her and come up brighter on him; and at a set time , all lights would go off a second; and a loud noise would be heard (the mirror quickly sliding open); then the lights in the hall would come back on with an amplified gorilla roar, as the gorilla ran to the front of the hall, and threw open the door made with bars; sending almost everyone running and screaming out the exit.
 
I went to the owners house once to pick up his truck; and I know it was "near" LA; but I can't remember which city in the area.  While there, he showed me his other sideshows. 

He also had a frozen Bigfoot or something to that nature, in a truck with Hiroshima and Nuclear bomb explosion photos on the walls. 

Possibly you have records of his sideshows. 

If not, I'm sure Butler Amusement's records would give you information about his gorilla sideshow, to update your files.