Here is a picture of the "selling/holding pit" at Cooper's in Llano. Notice the red plastic trays on which they place your meat directly -- no paper or anything, to take inside to weigh.
They have goat, thick pork chops, ribs, brisket, sausage, etc in there to choose from. The meats are cooked on the other pits in the yard. You can see part of one of them on the far left of the picture.
The selling/holding pit is to the side of the building. There is no front door as such. You stand in line and smell the smoke. When it is your turn, they open the pit door for you and the smell gets you in a feeding frenzy. You point and they cut. Then you go in the side door to weigh and pay and get your other stuff.
The concept I have for the farmer's market is adapted from this system.