So I decided to put my amp under my seat and make a box that will still fit under the jump seats because I always use them in the winter. The amp brackets are just bent aluminum that are bolted down with the seat bolt and the front of the amp is screwed down into the seat bolt bracket under the rubber floor with self tapping screws. Also I did have to take out the spring under the seat that helps with moving forward the seat but I can still easily move it forward without the spring in but I rarely move my seat so it wasnt a big deal. Enjoy.
The seat was all the way forward in this picture, you can't even see the amp with it about half way back. Also ignore the extra wire, I am replacing this wiring kit and putting it into my car so I didn't bother cutting it down.
Everything can be adjusted from the side no matter where the seat is.