Oh, yeah. I see it now. I can't really help you from this end mate. A few of my mates are general freight truck drivers and another mate owns a tow truck.
If you can talk to one of your local, more well respected tow truck, or better still tilt tray owners, I'd say they would have some valuable advice.
Just to make this reply a little more confusing I'll try to explain how a tilt tray truck might strap down the load. Basically they use one strap per wheel. The strap pulls each wheel directly sideways toward the closest side. Not diagonal in any direction, not sideways to the opposite side. There is also one more trick and that is they create a loop in the strap before putting it over the tyre. There are special straps to create these loops and they are used only for this purpose. And that's it. Not rocket science really. Every wheel is secure. That's all you need to do and it works fine.
Hope this helps.
I didn't see your reply there Bob. I'm a huge fan of chain, or what we call "rated" chain here in Australia. And I have to agree with Bobs' method as well. All good. Excellent advice.