Lumpy Volvo floor

I have a 780 and its the same way, lumpy , between the fridge and opposite closet. Since I don't want to remove the carpeting at this time, I went to home depot and got a piece of sheet metal, the thickest gauge they carry. It cut to a 2x2 foot section I think. It fits perfectly in the space on the floor.
I bought a rubber mat also in Home depot, the kind you use in the kitchen to sooth your feet while standing. I cut strips from the mat the size of the lumps on the floor , about 4 strips, then placed the sheet metal on top, then a piece of regular carpet over the metal. It sounds dumb, but it works.
I will do a more intensive job in the summer and correct it the right way.