I've been looking at different harness designs for the jetpack.
Some of them involve a chest strap with Fastex clips, which seems kinds cumbersome, bulky, and for those of us with pecs (or moobs) a bit uncomfortable. But attaching shoulder straps directly to the flack vest, and leaving the belt separate, is asking for the flack vest to slide back and cause the collar armor to ride up.
When I was in the Forces our rucksacks had an ab belt, with straps anchored to the belt going up over the shoulders to the pack frame.
Has anyone tried anchoring the shoulder straps to the flack vest, then two more attached to the vest to anchor to the belt? That would turn the flack vest into a load carrying vest and distribute the weight more evenly. The attachment to the belt could be semiconcealed to maintain an "accurate" look while keeping things comfy.