You don't need to make a campfire. (I mean, you can if you want to.) You can just start up enough charcoal briquets to make enough heat for the DO. Using a "charcoal chimney" works great. Sometimes the BBQ grill box at the campground is big enough for the DO, especially if you are just doing a single DO... (saves bending over, too!) Usually, though, you set the DO on the briquets, on the ground (inside a fire ring), with more briquets on top.
Here's a pic from one of Mike & Lori's DO demos, I think at the Oregon Gathering of 2006. Most impressive!!