My idea for a fun Winter event would be to build Christmas themed decorations around your farm, or various landmarks around the map, using bales. For an extra splash of color wrapped silage bales could be used as well. You would need to test your bale handling skills so only front loaders, wheel loaders, telehandlers, and skid steers would be the allowed vehicles. This could be done in stacks or a single level on the ground viewed from above. Awards could be given out for most colors used, tallest artwork, most bales used, most realistic, etc.