help with cerwin vega stroker

ok guys, here's the dilemma. I'm trying to hook up my younger brother. the vehicle is a 1998 gmc sierra extended cab. we already bought a brand new 12" cerwin vega stroker and a 2 channel 1200 watt kicker amp. he wants it to be as loud as possible and is willing to sacrifice space. so question is, where do we go from here?

 

it's a regular extended cab, the issue is we would like to keep the box to one side of truck. but there is only eight inches from the edge of the back seat to the back of the front seat. we thought about sitting it on top of the back seat which is probably the best option, being that the box could probably be about 2 cu. ft max, but I'm open to any suggestions.

 

Sorry about the rugged drawing thats the measurements of the back cab. we would like to stay under 34 inches for the width if possible.
The blue line is 32 inches
green is 16 inches
red is 6 inches
yellow is 8 inches
black is 23 inches.
Also there is probably about 36 inches above the top of the back seat.
thanks

 

Also I forgot the manual says to tune the port at 36hz and recommends 2.25-2.5 cu. ft. which we can do if needed.