Growing up in the 60s 70s music was and still is a part of my life. Joe Walsh stated every good rock song has a killer guitar riff in it. So to get to the point..I relocated the gas tank in the cab to an under bed tank. This left some real Estate. I am putting a bench seat that is fixed mount. Getting close some connections still to be made. here's some pics.. don't beat me up too bad .. it's only rock and roll but I like it.
Back massagers AND seat heaters! Funny, once I knew my truck's gas tank was going to be in the frame, a nice subwoofer (same size as the gas tank) was the first thing that came to mind! You have evidently taken it a step further...