My understanding is the backswimmers have a trapped air bubble on the underside, and they must periodically return to the surface to replenish. As such they travel in an almost sinusoidal pattern to surface and down.
You could mimick the downward travel path with a sinking line, not so sure how you could handle the bottom up presentation?
This idea has been on my to tackle list, but was saving it for winter and to try in early season lake fishing. I know Phil Rowley has both the BS and WB pattern, but haven't tried them yet...
Don't know if that helps much off at all, but I'll be following this...
Cheers!