BTW below are two pics I took some years ago when discussing this cross or not to cross and how using a single attachment point works in the real world. The first pic shows how the chains will ride up on each side of the end of the tongue allowing the end of the tongue to catch on the pavement and the second shows what the crossed chains look like. What the cross chains do is move the center of the crossing of the two chains up almost under the end of the coupler forming the cradle effect that forms the "skid" I have refered to and when tensioned will "lift" the tongue off the pavement while keeping the forward pull centered on the tongue and directly behind the TV. This crossing prevents the chains from being able to ride up on the sides of the tongue and allowing the end of the tongue to contact the pavement directly. This lifting will be fairly constant as long as you have sufficient braking applied and you don't apply the TV brakes so the TT is deaccelerating much faster than the TV.
UNCROSSED:
CROSSED:
Larry