I have found that using either insulation pads or a material like "hypervvent" keeps any mold from growing under the V berth cushions. Also seems to decrease the condensation. We take the foam pads up the side walls of the hull. We will have them at least below the shelf in the 25--and probably all of the way to the ceiling. We did that with the 22 and our first 25. It seemed to help in AK--at least if there is condensation on the sides of the hull, it does not run onto the sleeping system.
I also put "Dri Dek" on the bottom of all lockers to keep any items off the hull. Again, these areas are totally clean, except for what falls down under the Dri Dek.
I am trying a cheaper brand in the 25--we will see how it works out. West Marine is $6.29 plus tax, for each 12 x 12 square. The other is less than $3 each. My guess is that the "other" will be much harder plastic--but the reviews say they can but cut with scissors, so cannot be too hard? I'll review them when they arrive, tomorrow...