Your room size may not be optimum, but there's no reason you can't use Maggies in it.
If you have to place the Maggies close to the wall behind them (like less than 3 or 4 feet out), I suggest either diffusing or (only as a last resort) absorbing the backwave. You REALLY don't want to overdo absorption - much of the magic of a good dipole is the extra reverberant energy the backwave adds, and you want it to be full-spectrum energy, just like at a live performance.
If it's your mancave, you might even try a diagonal or semi-diagonal placement, the latter really staggers the distances to room boundaries.
Duke
dealer/manufacturer/longtime Maggie fan