My 1976 H 25 has a two part deck liner. The problem is on the top there is a core material however on the sides there is nothing except around the windows which is wood. There is a dead space all along the sides that I can put my hand in, which leaves great space for mold/insects and anything else that wants to take up habitation there. What is recommended to fill this dead/hollow space? Maybe Foam, etc? Does any one else have this problem? It is probably generic to the low cabin profile H 25, don't know. Thanks Jim