If you can keep in consistant, and not fight the fire IE: clean blue smoke at 225 throughout the cook, I would suggest not foiling till you pull it off. Foil it and let it rest. If you fight the fire, and keep having to add extra wood or coal to the fire you make more white smoke (bad creosote) wrapping it will salvage your investment.
If your a techno geek and want the thermometer, there is no need to even put it in the meat until 5-6 hours in. And i would only do that if your going to foil it at the stall.
If your going to foil it while you smoke, let the meat tell you when. It may stall 158-170 depending on the fat content i guess. When it stalls there for an hour wrap it.
Just remember if your wrapping it, it is sealing it, and braising it. This ruins the bark and changes texture of final product. Also prevents any further smoke from entering the meat. You might as well STICK IT IN THE OVEN on 225 because it has perfectly consistant even heat and doesnt require precious wood.
As far as what temp. Just pull it when its done. The bone should twist out with slight resistance,
A probe/knife, should slide in like it does a loaf of bread. Buy a .99 cent loaf of bread and stick a probe through the end of it. Get a feel for it.