Polyairs in a GU

Gday all,

I have two questions and hope someone can help me out

I fitted polyairs to my patrol last year, since then a Strong arm dual wheel carrier has been added.
Now when the vehicle is fully loaded the ride height is just below where I want it to sit, has any one fitted a 15mm coil spacer with polyairs... can this or has anyone done this?

Secondly the bottom spacer supplied with the air bags has a recess in it, I assumed that this recess faces the air bag and the locating bolt sits in the recess so it is not in contact with the bag to prevent chaffing, I have since been advised that this recess is supposed to sit on the dif housing so the bag is in contact with a flat surface. Can anyone confirm which way is correct?