Hello. If I may offer my humble opinion. I don't own a WSM but I know the reputation. They are built for heat control. If I may suggest, are you over thinking this a bit? If I were to try this I would add small amount of coals to the WSM and when the temp comes down into range add the jerky. I would also have a second larger fire going elsewhere. As the temp starts to dip, add a coal or three as needed to hold the temp. You might burn some extra lump wood but I would think it would be very little. I should think you could hold a WSM at 145-155 indefinitely. Would take some monitoring but start early some lazy Sunday morning and enjoy the process. Maybe while your smoking build a new spice rack while sitting on the back porch. Just a thought. Good luck. Keep Smokin!