I cook a pig in the ground every year. Its in the middle of the desert, and I have to bring a pick and axe and shovel every year to make this happen. The rocks in the area are limestone and sandstone, with lots of clay in the dirt. I have to bury the pig in the ground for 24 hours and let the residual heat from a 2 day long bonfire cook Wilbur. I spend a good chunk of time finding iron rich river rocks to put in the ground to retain heat. Its enough heat to make the pig safe(160-170), but I'd like the pig to be another 50-60F to start breaking down the cartilage and make it a true "meat falls off the bone" experience.

I've been toying with the idea of bringing a big steel or iron block to leave in the bottom to act as a thermal battery of sorts. I'd have to leave it in the ground though, which is fine since I use the same pit every year.

Do you happen to have some suggestions?