Simon, one thing I fogot to add with the picture was I used a bike carrier to support the securing straps to the vehicle this also allows you to increase the strap tension if the wheels need to be lifted higher of the ground,
I as said I used this for nearly three years and had no problems, the police have never stopped me, and the older kids (young adults) gave the car the nick name Ghost buster.
any way if you want more detailed info let me have an address and i'll put a cd together with more info.
I'm looking at using a trailer system to feed my growth starting with a small trailer and exchanging it for a larger one as they grow until they have enough to move into a van system, I like this idea as every system can be re-cycled
Alan