Note: This isn't my finished product since I'm gonna go with a wider board so I didn't bother hiding the wires or making it pretty. I did this in the dark, using my map lights, by myself in about an hour aka VERY EASY! I also did this without pulling out any plastic besides the actual cover to the location but my amps were already in that location. I was able to do the install without a saw because I had Home Depot cut the MDF for me.

I used:
16"x18" cut of 1/2" MDF board $8
4 metal straps (will use 5 next time) $3
Various bolts, nuts and washers $5
Staple gun & some carpet/material $0 had this stuff already

Basically gutted the area behind the driver's seat, installed the four straps, inserted MDF board to mark where the holes were going, drilled holes, covered amp rack, mounted amps, hooked up wires and installed amp rack using various bolts and washers.

Pretty easy and straight forward. The hardest thing for me was cutting the straps. They were too long in some places so I used a C clamp and a pair of pliers to bend it back & forth until they broke.

*A 16"x18" board will fit in the location without having to cut a chunk out for the wheel well. I am going to redo this tomorrow using a 13.5"x22" cut since, as you can see, I'm pretty tight on space because I have two amps.

If I knew then what I knew now: To maximize space on the amp rack, bolt the straps as close to the edge as possible. You can see in my installed pics that the bolts are pretty far away from the edges of the board. This will also keep vibration to a minimum.

 

Nice job......I also stashed my amp & cap in there....