Sorry guys really late to this one but
I was the pilot that dropped Gary Connery with no parachute into 18000 cardboard boxes. We had go pros on the skid ( clamp, backed up by 3 miles of duck tape) one attached to the airframe clamp and duck tape ) one on my helmet and one on the cargo hook.
The CAA inspectors were there in force, I asked them if this was legal in front of a load of people there view was as they were not permanent fittings and removable there was no problem ! So that is it from the horses mouth
Health warning here though be sensible with what you do and have a couple of attachment methods including wire locking !