Hi Jason.
I have a 15 year old Triton dual cab.Work truck towing the work trailer and also the boat and camper.Not at the same time though.

3 years ago I put a 1600 by 1200 toolbox permanently in the tray.
And a 100 liter water tank and 4 pole holders under the tray.
I spent some time going thru the options of a spring upgrade and lift.
Efs,Arb, Ironman,Emu, would they give me the ride plus weight handling I was looking for???
A mate put me onto a blacksmith here in Capalaba.He also does suspension. For racing vehicles and comp trucks.
Lifts them, lowers them,fixes the backyard sh!t jobs.
Wound up the front torsion bars to a height I was happy with, 2 inch or so lift, then put a trolley jack under the rear diff and lifted the rear to a height HE was happy with. He did some measuring then lowered the jack a little and said that would be the ride height with a full load and 150kg on the ball.
2 hours later and $400 lighter the springs are reset with an extra leaf.
With no weight and not towing the ride is firm. I can feel bumps thru my butt. But that is very rare.
I'm always towing something.
Towing the camper or boat the spotties aren't scaring the possums any more.
The ride is perfect with the weight on.
What I'm trying to say is find a local who knows what they are doing before forking out a lot of money on the web experts.
You may be surprised.
Rod
.