Estimating frost heave displacement?
Think outside the box.

If you are trying to minimize the distance to the deck to have max headroom, then attach the shed roof to the deck, so that water coming through the deck runs off.

Now build your shed but stop the walls a foot from the suspended roof.

From the roof hang 18" walls that have 1" clearance from the sides of the shed.  Stuff with  insulation.  Now if the shed moves up and down, the walls frm the floor telescope with the walls from the ceiling.