I'm still in the process of building my pair, so I'll leave that to those with more experience..
But a nearly cubic room is going to be rough to manage for any sysem, esp in the bass & sub-bass ranges. Your room is going to require a fair bit of treatment likely corner bass traps, diffusion panels, and suspended absorption panels hanging from the ceiling to break up the air space and any standing waves.
But I can imagine that if it is a living room, it's going to require more subtle or artistic tweaks that make aesthetic sense for your living space. (Book shelves, deep-backed paintings filled with fiberglass/rock-wool, Decorative diffusion panels, etc.)
Full open baffle setup will definitely make things easier to deal with since you don't need to worry as much about about the side waves radiating from the cabinets, and just the front/rear walls and early reflection points.
And I don't know your room layout beyond its basic space, but in order to reduce as many resonant peaks/troughs its a good idea to follow the 2/5s & 3/5 rule putting your speakers roughly 7-8' into the room 7' from each side wall. And find a place about 4-5' from the rear wall, or wherever you think sounds best.