Bivouac groundsheet, you are going on a bivouac or camping, your groundsheet will be your best ally for a good night's rest. Floor mats are less expensive than self-inflating mattresses, but they will insulate you from the cold and humidity just as much. The ground sheet, even light, takes up more space than a bivouac mattress. But it will be perfect for camping, in a 4x4 in the desert, in a rustic bivouac...