All the above sounds far too complicated for me lol anone wanna buy an Omega instead LOL
easy way to stop it going down to far . go to a caravan shop and get some spring rubbers , worked on mine

Be careful with these Rolf - I take it that you're actually referring to coil-assisters?
Whilst they're "OK" it must be remembered that the coil spring absorbs stresses uniformly throughout it's length. Assisters prevent the coil compressing uniformly, and the stress is basically transferred to the unassisted portions of the coil, and can effectively overload the 'unassisted' portion.
That said, I've fitted a combination of Monroe Ride Levellers (in lieu of the original shock absorbers) and Grayston Coil Assisters (merely to assist the vertical loading on the Ride Levellers).
Our latest 'van is just about the maximum towing limit for our TD (weight ratio-wise), and this set-up works reasonably well as can be seen here:

And here:

Whilst the pictures portray a nicely-balanced outfit, there's a tendency for slight oversteer, and I'm presently investigating the fitment of Cliffo's set-up.