More Sleeping Strategy
After a full, hard day of navigating and racing, the initial race-start adrenaline will have worn off a bit and you'll be left with your core physical condition to keep moving. Hopefully you'll have eaten a minimum of two to three thousand calories during the day to keep your engine from conking out. Depending on your body type, three to four thousand calories is probably a better goal.
At any rate, when you're starting to look for a dry patch of ground to sleep on, start packing in the calories. Ideally, you should eat something high in fat that will give your body enough heat to make it through a couple cold hours laying on the ground. You also shouldn't be too low on hydration, but you probably will be. Drink a liter of water before bed too. It will help your body clean out the lactic acid that built up during the day. What you shouldn't do though is drink a liter of water just as you're laying down. Start drinking an hour before you stop hiking so your body doesn't cool off too much from a huge influx of cold water. A liter of 40° cold water from a river will cool off your body quite a bit and conserving body heat is so important on the Classic.
If you're extremely hypothermic, you can try to build a fire to warm up but it usually takes more time than it's worth. If you're only mildly hypothermic, just hike a little faster. Being cold and wet is just part of the experience, don't waste energy trying to change it. Many racers do the whole race in a mildly hypothermic state.
Some people have used tarps or bottomless tents with mixed results. You'll need a stick to prop it up with and those aren't always around. You can use a ski pole but not everyone takes those along. Some people have just wrapped themselves in a small piece of visqueen. That works ok but you'll be even wetter when you wake up since moisture can't evaporate.
If you're lucky enough to get a fire going, find a way to reflect the heat back toward you. Here we're using an abandoned barrel as a backdrop. It didn't really help warm us up and as soon as it got light we put out the fire and started hiking again.