OK .Its probable that the front is 40 mm lower and the rear has gone 60 or 70 due to the camper con weight . Normally in this scenario we would try lifting the rear to 40 mm with spring spacers of different springs , Do you know what springs are fitted . Some manufacturers offer different weight rates for this problem
The Hub mod would be a solution there is no doubt but we can only safely slide the shock another 20 mm through the hub because it will hit the drive shaft if we go much more , Also the brake pipe, ABS cable brackets will need to be cut off , this is spot welded to the shock so its quite a job and there are always risks of shock damage .
Have you got the part number fore the springs you fitted ,