I fully removed the floor of my trunk. It is a light-weight, corrugated, plastic assembly. It has no ability to support anything heavy beyond that provided by the spare tire beneath it. Even if I was going to trust an inflated tire to support the station, placing 120 pounds of stuff over my spare tire can make it a bit tough to remove when required. I needed to re-imagine my trunk as the saying goes.
I had to slit the carpet along the back to remove the trunk floor but have since been told this is already done on some cars. The shelf is 3/4-inch pine as is the support foot which is under the visible row of screws. The shelf needs to support a lot of weight and it can. It is kept laterally stable by wire through a hole provided to keep the original trunk floor in place. Anytime the spare tire is in place that actually holds the shelf in place stronger than anything. The spare tire comes in and out easily. Easier, in fact, than before I removed the floor.
The nylon strap that holds the service module DOWN is one strap that goes through slots in the shelf, the foot and the shelf again. Once held DOWN the service module is rendered stationary by its weight, the cleats bolted to the shelf on either side and the nylon strap in the front and the back.
The amplifier is bolted to the angle iron which is bolted to the shelf. A strap keeps the amp from rattling.