I've done this roast many times with great success. I usually inject it first, used to love the Cajun Injector French Onion injection but that's hard to find now so use whatever you like, or don't inject at all. Use a rub or not, whatever you like. I then drape 5 or 6 slices of bacon over the roast and put it in the smoker. Sometimes I'll put a pan on the rack underneath the roast(s) and will fill the pan about halfway with red wine, with some of the marinade/injection mixed in, salt & pepper and a handful of baby carrots and a sliced up vidalia onion. Smoke with oak, apple or hickory until internal temp of 130-132, pull and slice immediately. The stuff in the pan becomes a nice au jus and the meat will remind you of prime rib.