It's really simple Venum. What you do is get a sheet of MDF or what ever material you want. And take out the carpet piece. Then lay the carpet on the wood and trace around it. One you have the outline cut it out with a jig saw or whatever and then divide it into 3 pieces the middle one will be the door to the full size spare. Then cut rectangle pieces of wood to be legs on the false floor - cut them out, glue and nail them on. Wrap with carpet and bam
Just remember the boot carpet is cut smaller on the driver side so you need to compensate for that - I didn't and now I have a little spot to his things hehe