Thanks all for the feedback.
I’ve smoked one on the BGE. Dry rub with garlic cloves inserted into cuts in the muscle. Used a water/red wine filled drip pan to prevent drying out. Low and slow until internal temp was about 145.
It was very moist and not unlike a good beef roast in taste and appearance.
This sounds like what I've got in mind. I can keep my Weber kettle grill between 200 and 250 all day with a charcoal snake. Thinking it might need about three hours to hit 135 at that rate.
