Brad came over to help wrap up the forward side skins so I was finally able to move on.
I used Dynamat and Dynaliner under the floors for soundproofing. The Dynamat is expensive and heavy, but works really well, so I am only going to use it in this location as this is where the exhaust exits under the plane. The Dynaliner is very light and not so pricey, so that will be used in other locations along the floors and side panels.
This is a horrible picture, but here you see the Dynamat (silver) goes on first and then the Dynaliner (black) on top of that. The Dynaliner is available in various thicknesses. I used half inch in this spot.
Then the floor panels were pop riveted in place.