MBL 101E placement in room

I've decided on buying a set of MBL 101e's for my home, but I'm now having a bit of trouble placing them in the space that I have. I know that since these are omnidirectional, I have to be more carefull about wall-coupling effects.

I've read that the MBL instructions dictate a minimum 2.6ft distance to the back wall and 1.5x that to the sidewalls, but I've also read on this board somewhere that the optimal distance is around 6ft from the back wall. (that means I need 9 ft from the sidewalls?) For my room this sort of setup is almost impossible, so I'm wondering how you all place your MBL's in your rooms? In most pictures I've seen of MBL's in real live settings it seems like the distance is pretty close to the back wall, maybe 3ft at most. I guess what I'm asking is: Does the quality of sound really degrade that much if I place the speakers at the minimum 2.6ft from the back wall? For WAF considerations, I'd like to be able to place them at that minimum distance if possible.
My entire space is 6 meters wide by 12 meters long, with the living room and dining room each taking up half the space.

Here's a random idea, can I place the speakers in the middle of the space, between my living room and dining room? But I think lower frequencies might suffer because there is no backwall to resonate?

Also, would it be horrible to place amplifiers and the preamp in a cabinet that's built into the wall (there will be proper ventilation - cooling and mesh vents) or is it better to put them on the floor like I usually see the big mono amps? I'd really like to avoid this as I have kids and I don't want them touching the hot amps or tripping over wires... what if I have a bench on top of the amps?

Thanks everyone for any help on the matter! =)