Help with 2nd VTF-2

[Badblue06]

Hi, I'm thinking of pulling the trigger on another vtf-2 in attempt to even the bass response throughout the room, but not sure where to put it. As you can see by my drawing, my room is really long (24'x14') and placement as been an issue from the beginning. I like to sit in the chair located just in front of the sub, but the bass is too intense for me there when the sub is properly set for the rest of the room. Turn it down and you cant hear it anywhere else. I really want the bass to fill the whole room. Will another sub help? Should I put it in the front of the room symmetrical to the rear sub? Did I buy the wrong sub? Need a bigger one? My set up is Polk Tsi500, Cs20 center, and Tsi 200 rears with a onkyo 709. The front speakers are amped and set to 40hz (in attempt to put some bass in the front of the room) the rest are 80hz. Thanks.