Don't know if this has been mention on here before but there is a fairly simple solution to this. 
  
Undo the 3 100m nuts.  Lift the back of the board and shim it out by a couple of millimetres (between the board and the hanger rear of the top nut).  Tighten the nuts, being careful to not over-tighten.  Think it heightens the back by about 15mm. 
  
Did this and I didn't scrape the boards once, even though I was riding with a passenger. 
  
BTW.  nothing wrong with sticking the pre-load to the top.  It doesn't affect the stiffness noticeably, just the ride height.