Dale...your plan is spot on; you may not need the full 2 hours/lb, but it is always better to allow more time and not need it, then to need more time and not have it! You can rest the butt for more than 2 hours if you finish early on the smoke. If you have a cooler, double wrap the butt in foil and place in a cooler surrounded by a couple heavy towels. Good luck and let us know how you make out.