More parachute stuff, if anyone cares...
First, some definitions -
Mains vs reserves - This is not simply 'front-mount' vs 'backpack'. Those bailout backpack rigs do not have the D-rings to mount reserves because they ARE reserves. The difference is kind of two-fold. One is intent. BASE jumping notwithstanding, in an aircraft related parachute situation the idea is to have a parachute that you do not intend to use. Sport or military jumpers making intentional jumps are intending to use their main. They carry a reserve that they don't intend to use in case the main malfunctions. An aerobatic pilot (such as Hayden) or military aircrew do not intend to jump. In effect, their aircraft is their main. Because their type of flying increases the possibility that they may have to bail, they take the bailout rig as their reserve. The other is classification and requirements. Sport mains, their design may include factors to increase flight performance that might also increase the potential for malfunction. They are generally packed by the person jumping them, whether or not that person is a rigger. They do not have riggers' seals or packing cards. Reserves are designed primarily for structural integrity and opening reliability and have to pass FAA TSO tests for such. They are required to be packed by riggers, and have seals and packing cards. Again, those backpack bailout rigs are reserves.
Gutter gear vs piggyback rigs - 'Gutter gear' is the old type, with the backpack main and front-mount reserve. Piggyback rigs are the more modern type with both the main and reserve on the back. While the first piggyback rigs came out in '64, it was a long transition before they were the prevalent experienced sport rig which was about the mid-seventies. In Cooper's day in '71, there was probably a fair mix of them among experienced sport jumpers. Students still primarily used gutter gear until about the mid-eighties.
Instructional methods - In Cooper's day there was no AFF (modern freefall training method) or tandems. Although there were precursors and tests, those methods didn't become prevalent until the mid-eighties. Before that all student training was static-line programs. You generally did 5 static lines, then a clear-and-pull, then increasing freefall delays starting with 5 second delays. For that method, the instructor does not jump, but stays in the plane and watches from there. Generally, an instructor should not need to push the students out. The students are there because they want to be, and usually they go. But sure, occasionally a first timer might hesitate in the door and require 'assistance'.
-------
At first, the idea of Cossey using a bailout rig to instruct seemed odd. Usually an instructor would wear his sport rig, put out his students, then jump himself. But if Cossey's sport rig was gutter gear, that might be cumbersome. He might well have chosen to wear his bailout rig because it is lighter and doesn't have the front reserve. In that case he would put his students out then ride the plane down. As for moving the ripcord handle - Sure, if he has to 'assist' a first timer with their exit, they may panic and try to grab something, which might be the instructor, and they might grab the handle. I've seen that happen. So he might move it to be out of the way. But there is only so far he could go with it. The handle is located on the main lift web, which is the part of the harness that goes over the shoulder, then down your ribs to the hip juncture. Usually it is at chest level, and 'inboard', which is in between the lift webs, on your chest. The only two places he could move it to would either be lower, more down by the hip, or he could mount it 'outboard', to the outside of the lift web, which would put it kind of near your armpit. According to something Flyjack posted today, it sounds like the latter. Also, the ripcord housing would usually route over the shoulder, but it also sounds like he re-routed it under the rig, where it would come up from the hip area. Those modifications might require FAA and/or manufacturer approval, as R99 said. If he later sold such a rig to Hayden, it would have been easy for him to re-locate the handle back to it's normal position. In any case, it would be readily apparent to whoever was using it where the handle is. You'd put the rig on, and touch the handle a few times to get familiar with it. In the immortal words of Larry Yohn, one of my early instructors, "It's not that fucking hard."
If the handle was indeed outboard, Cooper may have chosen that rig precisely because of that. If he had a bunch of stuff (money) tied to his front and chest, it may have covered/interfered with an inboard mounted handle.
------
I don't do any social media, I'm not on facebook, so I can't use Eric's page. If anyone wants to post any of this there for Carr's perusal, be my guest.