I have a Magna ES TL (Wagon) and an amp that measures about 30x20 cm.
Can anyone suggest a good place to mount this on the car that is hidden and secure without making a lot of holes in the carpet/interior?

My last car I drilled and screwed it into the back of the rear seats, but this would not be great.

Please feel free to give ideas by example in your ES TL. (Wagon or Not.)

just mount it under the passenger seat
or on the back of the rear seat

I don't want to have it in plain view if possible. Under the front passenger seat prob isn't good as I have a factory map drawer there. Driver seat is electric so i'll stay away from that. I don't really want to mount it on the back of the read seats as it will be in plain view and make holes in the back of seats. Any more ideas? Anyone tried to mount one under the boot floor in a wagon successfully?