I have a friend who added some type of suspension assist on the rear axle. I don't know what brand he used but he said that it helps a lot. On the Escapees forum (or perhaps in the Escapees magazine) I saw that the overload springs, above the regular rear leaf springs, are often poorly adjusted. If you have overload springs and there is more than three inches from the top of the U-bolt that goes over the overload spring to the bottom of the U-bolt that goes below the regular leaf spring, then it is poorly adjusted. On my springs the distance was over 4 inches.
The message on the Escapees forum was that after adjusting the open distance on the U-bolt the rear of the RV was raised and handling was greatly improved. With this adjustment you could not change it easily depending on road conditions.