Just the winch cable, this way I minimize the amount of straps used. I've thought of the tire strap system, just thought there would have to be to many tie down points, and I'm thinking that your machine has to be in the same position everytime? Someone once told me that the straps should be strapped at a certain angle to minimize movement, I'm thinking more horizontal (45 degree angle) than vertical (up and down). but then yet this might just be common sense
hope this helps