I don't know. I think if it were me, I'd try to do the bypass, including the wiring of the headlight, and see how long it really takes. It might take a few hours the first time you do it, but after that, you'll have the exact procedure down and it will go a LOT faster. What if you could knock them out in a half hour? I think in the long run you will be happier to have them all be decoder-free. They will run better on your DC layout that way.