This is a task the Boy Scouts could do while you beat eggs mike and cheese together. Next, you find a level spot of ground. It's what garden rakes are for. Make sure there is nothing you want growing under the box. It won't be there afterward.
Men can handle rakes.
It gives them something to do. Then, you add a thick cardboard sheet to the ground and cover with a few sheets of aluminum foil. They tell me drip pans for car engines are good. Not the plastic ones. I didn't have time to go to Kragen's.