If you get 'blisters' under a pad during long term storage its not a result of pad moisture but the result of porous/permeable hull. If a hull 'blisters' when on a wet pad, what will happen to the very same area when the boat is in the water for several months.(nl)Rather than a moisture problem, Id keenly suspect that previous improper blocking has partly delaminated the hull at the where the hull is blocked; and, the surface contact of a 'soft face' pad would reduce any point-to-point contact (high stress or high pounds per square inch of contact) and would change that situation into a more 'equally distributed load' ... or less pounds per square inch pressure against the hull. But you'd better consider to assay / fix the 'problem' thats in the hull laminate, first.