When you meet your buddies at the designated parking/meeting place, be sure that you all bring your ID's and proper hunting licenses, camping permit, whatever is required. Not having all that when required to produce it will really ruin your trip.
I also suggest that you each take an extra quart of clean drinking water, over and above what you had planned on taking. Your body will need extra water in the cold, and don't eat snow or ice, always warm it to liquid if the temps are low enough to produce these conditions. The reason being is that your body will expend more energy raising the temperature of ice or snow to the point that it can be absorbed and that means you have to ingest more calories to break even.
As others have suggested, bring something insulate yourself from the ground at night or get yourself up above the ground. A ground tarp will keep the ground moisture off of you plus you can fold it in half and put leaves, grass, stuff like that to help insulate yourselves. If this is going to be a period correct camp and it will be cold, wool blankets are your friends.
Lastly, when skinning/gutting a hog, always cut wilt the direction of the hair, not against. The bristles will dull a knife faster than you think so don't try and shave a hog with your hunting knife. Bring a small wetstone or something similar to touch up the edge of your knives as well as some oil, grease or rust preventative.
Good luck, hope this helps.