I have an Ava 2015 acro base and have been thinking about ways to fly with a 3rd rescue for training tricks with a high risk of falling into the wing/lines where I may not be able to use my base. Unfortunately this harness has no spot for a 3rd rescue (I'm aware that the newest version of the harness does have this). Using a front-mount is no good because clipping into the carabiners would add a major risk for using the base, and there are no attachment points at the shoulder to add in risers.
I've considered wearing a lightweight climbing harness ( https://campfour.com/products/black-diamond-couloir-harness ) underneath my harness and attaching a front-mount rescue container to the belay loop. While obviously not ideal, the harness is plenty strong as a 6G opening shock of a rescue is similar in force to a typical lead-climbing fall. The downside is that you by would be suspended by your waist instead of shoulders so a PLF would be harder. Can anyone think of a risk that I may be overlooking?
Alternatively, I've considered making or modifying a webbing harness to add in shoulder attachment points, though I would feel better about a professionally made product if a lightweight version exists. The last option would be if I could find a rigger to modify my harness to add full strength attachment points at the shoulder.
I fully recognize this is somewhat sketchy, but having a 3rd rescue for the event I end up in deep shit seems better than not having one at all. Does anyone have any ideas/recommendations to pull this off? Bonus points if there is a way to use a rogallo, since I'm told the risers for the second rescue are too long for one.