Ive tried 3A signatures in a number of places in the room- following the guidelines in the manual, and just experimenting.
I think you will do ok, but with that room set up I would instead buy the 2CE.. I just don't think that you are going to notice much improvement of the 3A Sig when you have the speakers that close to the walls.
In my room I have the speakers 6' from the front wall, and 3.5' from the side walls.
I still had to treat the room acoustically in order to get the best sound I can here.
I tried many times with the speakers close to the front wall, and each time I was not satisfied until I pulled them out at least 4 to 5 feet from the front wall.
If you have the space- try it
Will