I know of a bunch of lads who camp out at Mulsanne every year. They have an enormous metal barbie, with a rather heavy cooking grate. To save on travel space, they bury this, and as far as I am aware, have been doing so for at least 10 years.
A word of warning though, should you decide to start digging looking for buried treasure, a lot of people also dig their own cess-pits!!! So be warned, just because the earh looks soft and freshly dug, does not mean buried treasure of the valuable kind.