Yeah, what Bob said: deadman anchors buried in the snow. Depends on how dense the snow is, but form 12 to 30 inches long, buried perpendicular to the guy line. Use (and practice beforehand) the clever knot Bob shows in his link or just a regular taut-line hitch but with the knot well above the snow level (so you can untie the know and pull the unknotted line back out if the stick gets iced in).
If you need to stick to slightly more secure, throw a few shovels of snow on it and stomp it all down. If you want it to be bomber, then wet down the snow a bit and when it refreezes, that stick won’t move, at all, till spring.
With a party of 19, that’s a lot of sticks. Bring a good saw and keep an eye out for good sticks / branches as you approach your camp.
Your pulk: Get some X-C ski glide wax. Clean the bottom of the sled, and coat the bottom with glide wax in your garage before you go. Any road grit from being on your roof top with slip right off when you hit the trail. More importantly, it will be a lot less work to pull and greatly the reduce the chance of it icing up on you which really sucks. Bring the glide wax along, because other people will want to do, too.