I cross mine too (not a VW) but ... the problem with crossing is that if you lose one strap, the other one at that end will pull the car to one side of the trailer as it bounces along, slackening that remaining one and then you only have one end of the car tied down, allowing it to now move fore or aft.

But due to the inability to route straight, and the use of T-hooks requiring lateral tension to stay in place, there's not much choice. Just check them every stop.