Your room is plenty big enough. However, dipoles should be, if at all possible, at least 5' from the wall behind them. That 5' distance creates a 10 millisecond delay of the sound coming from the rear of the speaker in relation to the sound from the speakers front side. Sound travels roughly 1' per millisecond, so the sound from the dipoles rear travels 5' to the wall behind it, and another 5' to return to the speaker plane---the rear sound is therefore delayed 10 ms in relation to the front sound. A 10 ms time difference between two sounds is required by our ear/brain to perceive those two sounds as separate events. Anything less than that is interpreted as one event, and the rear sound will be perceived as smearing of the front sound, rather than the separate ambiance a dipole can provide.
As for distance to side walls, I have and listen only to planars, which have a figure-of-8 radiation pattern---sound to the speakers two sides is cancelled. They can therefore can be placed fairly close to side walls without a sonic penalty. Non-planars are a different story.