I wait till mine hit 185-190 then probe till butter like feel. Wrap as you do and cooler, so far this has worked with great results, However I use a water pan between the fire and the racks. What are you cooking with? I will usually put some butts on as not to waste fuel, the temp of all the meat in the cooler will keep everything nice and hot for a few hours. I also have put about a tsp - tbsp of apple juice in the foil with pork, Beef broth with Brisky. This may or may not help but it definitely does not hurt.
I Eat Burgers for Breakfast