Boy Scout Troop 604
The adult patrol is the Rattlesnakes. Unless it is a family outing, we typically have all the adults in one patrol. Even if there are a large number of adults (>4), one patrol still works as long as you plan cooking items (pots, fry pans, stoves, etc.) accordingly.
Another option is to have one or more adults join the Scout patrols for eating. The advantage to this is you are easily available for coaching while the Scouts are cooking. This can be especially useful with new Scout patrols. The disadvantages are that you will have a tendency to "take over" (you CAN'T let that happen) and that you will eat what they select and cook.
Other than cooking, adults typically sleep by themselves in their own tents -- we don't bother arranging "tent buddies".
How To Plan a Camping or Backpacking Trip