For all the safety nazis. Think of all the enclosed van type semi trailers you meet on the street/hiway. Not a single one has any cargo tied down, not one. There aren't even anchors in the trailers. So before you get mouthing about a 450 lb. sled in a trailer being dangerous, think of all the 5-50,000 lb. stuff that is sitting loose on the floor of commercial freight trucks. A 500 lb. sled shifting 2 ft. max in a trailer isn't even noticeable. Mark