Macka,
Firstly I have a number of questions.
# Is there a particular reason you've ordered an Off Road Van when you don't as you say intend to do anything extreme off road. Wouldn't a less expensive Dirt road van been a more suitable option?  I'm not being critical, I just wonder why.
# You say the Trakkie will weigh around 2700Kg. Is that the ATM shown on the vans compliance plate?
# Ball Weight in the vicinity of 220Kg.
With a loaded van (Including water in tanks and full jerry cans etc) of 2700Kg and the weight being correctly distributed throughout the van. the Ball Weight should be around 10%+ of the overall weight of the van. If loaded to an assumed ATM of 2700 Kg then the Ball Weight should be around 270Kg+.
# Beefing up the rear suspension with stronger springs or air bags will eliminate any rear sag, but won't put weight back on the front suspension that was removed when the van is hooked up. Only a WDH can achieve that.
With a Ball Weight around 270Kg even a Hayman Reese 550 WDH will be insufficient to achieve the desired result. You will probably have to look a the larger 750 WDH which can handle ball weights from 250K to 350Kg.
I hope the above answers your questions.
Cheers, ozjohn.

Maxka.
Think of the tow vehicle as a childs seesaw with the rear axle being the fulcrum (pivot point).
If you place a child (Van) on one end it goes down and the other end (front of vehicle) goes up.
If you add something between the board and the fulcrum (Car & Axle) the car rises at that point, but the end of the board with the chdils remains down and the other end remains up.
To return the board (Car) to level you would lift the end of the board with the child on and thus the other end of the board would go down to level the board.
A WDH does exactly the same. It lifts the rear of the vehicle behind the axle (Fulcrum) and thus allows the front of the vehicle to return to it's proper position.
"Bingo", the load applied to the rear of the vehicle by the van has been distributed over all four wheels and safe steering and braking retored.
Cheers, ozjohn.

PS> A WDH doesn't alter the ball weight. What ever weight is applied to the ball by the vans coupling remains the same.

Macka - with the reports of dual cab utes breaking their chassis I would look carefully at adding air bags. Those I have seen reports of have had air bags fitted. With standard suspension the weight is carried on two points on each side of the chassis. When you add air bags you are changing the stress points on the chassis to one over the axle. the more you pump up the bags, the more that point carries. This makes a new see-saw point on the chassis. Add air bags at your own peril - despite what those trying to flog them to you say (if you listen to that sort of speil you will probably end up with Hyclones fitted to your vehicle.)

Unless you overload your vehicle then WDH will suffice. When you are forced to remove the WDH bars you will be going so slowly you will not have to worry about the load problems.

Macka, only just opened this site. Sorry for the late addition to this forum. I have a Ford Ranger 3lt Turbo Diesel, Single Cab, 4x4, with a full alloy canopy, it weighs in at just over 2600 kilos with my load, or if I fill the 5 jerry cans of both water & diesel you can add another 200 kilos to this load. With the Ranger & the BT50 being the same car I presume the same holds true for Mazda as it does for Ford. Ford will not allow (ie warrant) towing over 1800 kilos unless with a WDH. I have recently fitted air bags to assist the rear suspension. I found that towing a camper van for 12 months (only 1600 kilos) the rear leaf springs started to flatten out, a common issue I have been told. Could this be similar issue with BT50s? Anyhow, with the new van coming in at between 2100 & 2200 kilos, the fitting of air bags coupled with the WDH, the van tows easily, tracks well & well within the 3000 kilos that Ford advertise the Ranger able to tow. Just as an aside, with your van coming in at 2700 kilos it might be advisable to keep an eye on the weight of the BT50 as a weight relative to your van weight.

Regards terry