Jaimie loves cooking, and he loves Rendezvous camping. One year, when we first met, he was asked to cook a pig at a Rendezvous for someone's graduation. He decided to dig a pit, build a tripod, hang the pig from the tripod and cover it with canvas (continuously kept wet so that it doesn't burn off). He dubbed it "Great Plains Style Barbeque." It was such a hit that he has since cooked many lambs that way as well. I've also seen his friend cook this way and cook ribs on grill grates hung over the fire this way. This weekend, he cooked a small lamb Great Plains Style.
Basically, you start a fire and get it burning slow and hot, which is when it's ready to have the meat put in. It's got to cook almost all day, so hopefully is a comfortable day to be outside. Keep the hose nearby (when we did this at a Rendezvous, we spent 6 hours hauling water by bucket, but that was for a large pig rather than a small lamb), so that you can keep the canvas constantly wet. Jaimie likes to toss mesquite chips into a cast iron pot so that it gets a mesquite flavor to the meat. Check on it occasionally, taste testing as necessary, and then enjoy. Of course, put out the fire before leaving the area.