Get the R hooks from someplace like
www.awdirect.com so that you hook these into the frame slots instead of the straps themselves - as the hooks on the straps will tear the holes in the frame. Hook to the R hooks inserted into the frame holes - that's how the cars are transported by Reliable and "towing professionals".
We don't cross the straps front of back, but we're on an aluminum treadplate floor and Henry has been accused of stretching the frame on the cars 1/4" every time he ties it down..... But - it's never moved.
10s or thousands of towed miles with no issues.