Originally Posted by
GeoffH
Based on my own experience, for such a large van, you need to get the Caravan's drawbar as neutral on the D4 as possible.
I've recently completed a 1.5 year trip around Australia with my family using our 2015 TDV6 D4 tug, towing a 3.5T Kimberley T3 dual axle off-road variable suspension van - not unlike your Bush Tracker in physical size & weight.
We ended up moving to instal a Mitch hitch male-mount on the D4 in replace of the standard LR hitch mount (which is far too low for such a heavy & large van) and throughout the whole trip, we never had one issue with towing, stability, dampening, swaying or pitching. We did the Gibb River Rd, Birdsville Track and several other explorer tracks on our trip ...all without a single problem. The key to effortless towing with such a large and heavy van is to ensure you align the height of the van's draw bar to as equal (or near too) of that of your D4's hitching position as possible. This is why the MitchHitch (Mitchell Bros, Brookvale, Sydney) D4 hitching solution worked so well as it's fixing pint & alignment raises the hitch point equal to your rear bumper bar - almost equivalent to your BushT, & in our case, our Kimberley.
The rear dampening issues & pitching you mention is almost certainly caused by your "ball weight" and the angle of the drawbar attached. The standard LR 4 hitching point was purposefully designed as low as it is for the main (not sole) purpose of towing horse trailers and floats. If you have ever towed one of these trailers, then you would know they are (typically) much lower to the ground to allow horses to get on & off the trailer much easier - therefore the lower hitching point on the vehicle.
This design however did not put to much consideration into towing a large & heavy caravan with large wheels & off-roads tyres - hence the downward angle of your draw bar. Equal this all up and your D4 will have a new lease of life when towing. Good Luck...