Neat setup awill4x4.
Curious to know what the rough cost of the engineers report was?
I've been thinking about upgrading our Jayco Eagle to a 50mm axle, 12" brakes, along with springs. With the few extras fitted and what we take camping, I'm betting I am way too close to the GTM of 1385kg.
The cost of engineering was $660 for my setup.
I don't know how that compares to other engineers but I just wanted peace of mind that I am towing a perfectly legal van.
For anyone going down this line just make sure to keep all receipts and try to get them to show maximum loadings as in weight etc and part numbers if possible.
The tyres were a bit of a limiting factor for me, I went for 205R16 Bridgestone Duellers with a load rating of 110 but I have to run high pressures around 50 psi (engineering requirements).
In hindsight I should have got maybe a tyre around 225/75R16 (roughly same diameter as 205R16) with a load rating of 115 then I wouldn't need tyre pressures as high as I now do.
Being an "onroad" van the wheel arches aren't very big so going much larger than the 225's probably isn't feasible.
Regards Andrew.