While I know it's highly unlikely to perfect, I am looking for a way to maximize this, if at all possible in 11x14 room.
This may sound nuts (oh heck, I've just chambered a bullet, someone's going to flame me over this no doubt).
I listen to orchestral music quite a lot, and I really love movie score. Try using your long wall as the front wall, try diffusion entirely on the front (long wall) with deep use of absorption in the front corners for lower frequencies. Absorption if possible on the top and bottom edges of your now long front wall.
Absorption on the back wall, however, if you're going to play with diffusion do not use quadratic (it's not going to give you benefit at all, certainly not here, it takes distance to develop an effect, which you do not have). You can get binary amplitude diffusion to work at extreme short distances, with absorption. If you do trial BAD with the holes, use 1/2" holes it helps with lower frequencies.
Set your speakers off the front wall, through trial and error and keep them in from the left and right boundaries ( I would start with 7 foot apart), this is why I am suggesting using the room the wrong way round. You could also try using absorption on first reflection points on the sides as well to open up for the larger sound you're trying to portray. The sides of the room, those reflections are a dead give away sonically on room size.
Your seating position would be not far off the back wall, giving you an equilateral triangle with your speakers, if you do the ceiling possibly try mixed absorption & diffusion.
If you have someone who can help you, a handy mirror to visually see the first off axis reflection points of both speakers (not just the closest one) on the side walls should be diffused or absorption treated.
It's absolutely a compromise, it's one that's worked for me and others, trying to get what you asked for.