I think I've got a habit for ideas like this.
Why not rig up a cape/poncho as a small parachute, maybe fastened to one's back, to act as resistance for long descents? Would be a bit noisier, but you'd be REEEALLY visible (descents always HAVE to be winding, don't they?) and there'd be less stress on the brakes/rims/arms.
Besides the absolute silliness of it all, of course.