I've seen a similar idea using a small elastic band to hook a small crayfish for live bait fishing.May not be "your" idea, but if you use it and catch fish with it, you can make it part of your tackle routine.
I almost never have that problem with senkos. if the fish are there, they will hit it...
o-rings for senkos have been around since senkos came out many years ago. in terms of trying to imitate a senko with a fly, why? The senko works because of the gentle sashay action it has thanks to the heavy salt in the plastic...a properly worked streamer can have WAY more action and work better than a senko.