We did that cheapo tri-plane on 6/15/80 at the old SOD Farm, east of Tampa.
We used student rigs, 28' 7TU cheapos with full gutter gear. The three of us in the triplane were Ferd Boger (RIP), me and Mike Lewis. Al Ramsey took the air to air photo. We even did a 4 stack with two 28's on top and two Strato Stars below. Shortly after this photo a few of us bought some 28's and modified them. We gutted the lines that ran through the canopy, installed three ring risers, diapers and hand deploy pilot chutes. They would fit in our existing Strato Star/Cloud sized rigs. Much safer. Those were crazy days!
I would love to get a scan if anybody has one.