Cool, nice to have another Iowan around these parts.
I'm not a sub expert, so maybe some of the others will jump in here, but for that size room the 125 would work, but not give you a true HT experience, especially in the Low Freq. Effects category.
My HT/recroom is about 30' x 30' with 9ft ceilings and the HT area is recessed in one of the corners. I've had the EP350 for about a year, but just sold it and bought a EP500. Before I moved everything downstairs I had the 350 upstairs in a 15 x 20 with vaulted ceilings room. The 350 did fine downstairs, but was not really enough to fill the entire room, so debated on getting a second 350 and place it opposite the room to balance out the LFE's. Instead I sold it and bought a 500, WOW, I luv this 500, unbelievable.
Ideally you would not want your sub behind the tv, but maybe your limited on placement? Sub freq's, especially below 80hz, are not directional, meaning you can't tell the direction of the low sounds. That is how it is supposed to be, and there is no need to place the driver facing the listening area.
How do you have your crossover settings set on the receiver/sub?