Before you go buying 1000kg spring packs mega, think about this.
If you have a pack to suit a ton, when your only taking the boat there will be no give in the springs, and you may as well weld the shaft to the chassis...
I would keep your lighter rating, and attach some variable load shocks..
There an air shock which work like the bag style for coils.
Only a couple of hundred and a few hours welding and vola.. done.
When your empty you have a nice ride, when loaded it maintains its height and still rides nice.. and is completely adjustable to suit whatever the load..
Kallen Westbrook
Owner of
Westy's Accessories