Is my room OK for Magneplanar 3.6's

If possible in a room that size without being in the way, you might try a less commonly advertised but highly effective (for best sound) alternate placement strategy for the Maggies for best results. That would be about 1/3 to 1/2 way or so into the room and only a foot or two from sidewalls. You have to play with exact placement within these parameters to get optimal bass results.

Otherwise they may work but not reach their full potential with the more conventional placement closer to the rear wall for bass re-enforcement in a smaller room like that.

Good idea to consider a near field listening solution with those in this room.

It'll work but practically big maggies with a sub is probably overkill. Go with the smaller mmgs and save money and provide yourself the most flexibility in setup as needed.