While I think the 2 part is probably the best, I am still looking for an easier method. I recently found a product called Marine Evercoat Sealant Foam, by Evercoat, which they advertise as waterproof. I called the company to inquire about the density and the Tech I spoke with did not know. They are supposed to be checking with their development people and are to call me back. I will advise once I hear, if I hear. But in the mean time, has anyone tried this product? The negative on the Great Stuff seems to be related to it not being waterproof, this in the other hand is by a marine company and is water proof. I am intersted but still waiting.