I've got the clam 5600 and I took two of my old skis and cut them to be just a bit larger than the house and screwed them in. I mark my holes before I raised the top up past the first pole and I always use ice achors in the wind. I've been inside it once on ice with no snow and a big gust of wind took me for quite a ride. Reservour was still open water in the middle and I gaurantee I could have won an Olympic Speed Zipperring medal trying to get out of that thing! I too use climbing anchors that are self taping and the ice pops through the center. Really slick and you don't need to care a heavy hammer or drill. Go to a climbing store and ask if they have any anchors that are a year of two old. I got 5 for about 15 bucks!