How about a regulation that is specific to select terminal areas? For instance:

Skokomish River, Aug. 1 - Oct. 31, Hwy 101 downstream to mouth, maximum leader length between weight and hook = 24".

That shouldn't affect legitimate drift fishing, spinners, spoons, jigs with or without a bobber.

The only legitimate fishing method that might be adversely affected that I can think of is fly fishing, in which case a reasonable exception might be floating line and unweighted fly, and then a standared 9 or 10' leader wouldn't lend itself to flossing.

Sg