Sancho is a Spanish name and it means Saint. In slang it means the other man, a guy a girl is cheating with. Sancho means sancho in English as well as Spanish. Pearl Yamada.
The general rule of thumb for a horizontal smoker is that the firebox should be 1/3 the size (volume) of the cooking chamber. These are just guidelines based on years building smokers but your mileage may vary! Cooker Chamber Type & Size.
By having a wider coping you can use the fire pit for more the just a fire pit. So at the 36 inside diameter with say 14 coping that gives us an outside diameter of 36+ (14x2)= 64 inches. SO now figure how much room you want to have around the fire pit. Lets say 4' for a sitting area and such. That now makes the area you need to donate to the project 48 + 48+ 64= 92 which is a 11 foot circle.