I'm with PixMan on this one. I have 3 bikes, 2 of them sit in the basement ALL winter and I never have a bit of problems with flat spots or tires degrading. Don't over think it. Make sure the tire pressure is up and just park them where you want. If you're worried about concrete, cut a couple small pieces of plywood and position the tires on them. Done deal, ride snowmobiles to your hearts content.
2011 Tiger 800
1998 Daytona T595