This is taken from the blog at solarcook.net. Excellent idea, I'm going to have to try this.
Sun Cooked Breakfast
Campers and preparedness minded folks often ask about making breakfast in a Sun Oven. There is a way to adjust a Sun Oven to allow it to heat up with the first light of day. Early in the morning the sun is very low on the horizon and the reflectors block the sun from reaching the chamber. If the leveling tray is removed the Sun Oven can be turned on its back so the side with the adjusting leg is on the ground or table top. In this position the wall behind the thermometer becomes the floor of the oven. A trivet or small rack can be placed behind the thermometer and pots or pans can be placed on the trivet.
(Keep in mind that if the leveling tray is removed, pots and pans should be placed on a trivet, not on the floor of the oven. To cook evenly, there must be air flow all the way around the pot. A trivet will allow air to pass under the pot and ensure an even heat.)
Placing the Sun Oven in this position can also add cooking time at the end of the day. The only drawback of cooking with the Sun Ovens in this position is that you need to stand on your head to read the thermometer!