I've never accepted that ported speakers can't be used near walls just because the ported is in the back. The surface area of the bubble when you move out just 6 inches is many times (25 - 100) that of the area of the port (depending on the port size), so too then is the pressure drop and therefore the effect.
OTOH bass response on ported designs drops off at 24 dB/octave versus room gain of 3 dB/octave, so designers typically add a bass boost around 60 Hz to try to compensate. And of course anytime you move the speaker closer to the walls it will reinforce non-directional (bass) frequencies as you go from 8 Pi (open) space to 4 Pi (against one wall) space or 2 Pi (two walls) space. It's this 60 Hz designer boost added to the wall reinforcement that causes most ported designs to boom.
In any case in this small/square room I'd try to stay below a 5 inch woofer and keep the tweeter as close as possible to aid in driver integration. I'd also look into single driver designs. Hopefully you don't have many furnishings in the room, so you could try a pair of The Horns (see Ed's circle below). They can sound good, but can be fussy to set up (balancing rear corner bass reinforcement with imaging). They're small/short floorstanders and so can get "lost" around furniture.
In a small room, you'll have a hard time balancing excessive wall reinforcement, providing sufficient room to create a stereo soundscape, avoiding bass boom from your head being against back wall, and having enough distance between you and your speakers to allow for driver integration. I surely wouldn't "over invest" in this room as you'll never be able to good really good sound from it (and I listen nearfield). Have you considered headphones? (Seriously.)
In any square room, I'd suggest trying a skewed speaker/listener arrangement to minimize first reflection issues. Next I'd try to make opposite walls "live" versus "dead" via absorptive panels. Even partially filled bookshelves can be used for diffusion.
