Have a read of GOJEEPS trailer build and set up of his trailer suspension / brakes .
Thanks edz. I was looking for that site last night but could not find it. He has added "Willys hot rod" to his web address since the last time I looked at it. He has been building that thing for years and it looks like it is nearly finished.
http://www.ozrodders.com/forum/viewtopic.php?f=2&t=20217&start=2430 The engine seems to have sufficient power to keep up with the traffic and get him to camping sites in a hurry.
His trailer suspension design will change the angle of the axle slightly in corners. Your typical short in length trailer springs will do the same thing but in the wrong direction. Car springs are long with the front mount down low and the rear up high. When fully loaded they are flat or very close to it. This causes many owners to think they are not up to the job. As the car goes into say a left hand corner, the car will lean to the right. This will cause the spring to compress even further and take the axle up and forward as it pivots around the single bolt through the front eye of the spring. The other spring will have weight taken off it so it moves the axle down and back. The axle in now pointing slightly in the direction the car is being steered. This turns the wheels back into the distorted tyres and reduces their slip angles. That in turn reduces the chances of the car oversteering and sliding its tail out instead of understeering as the manufacturer intended.
When you look at the short high arc springs commonly used under trailers, you will see that the front and rear ends of the spring are mounted at the same height under a flay surface. As the spring flattens in corners, it can only turn the axle the wrong way and increase the chances of the trailer oversteering.
This is not all that much of an issue with small trailers like campers but it certainly is with long heavy caravans.