The first step I took in working with a restricted space was in the speaker design selection. Speaker (and baffle) size is only one factor and can even mislead. Some speakers of equal size are simply going to demand a larger room space than others. One issue is how the speaker treats bass. You might want to avoid floor standers that have bass vents firing out the back side, which by design critically use the space/distance between the speaker and the front wall. Front-firing speakers usually require less reverse space and can be positioned much closer to the background (front) wall, thus giving more space in a tight room for the listener's space and the essential acoustic blend and balance. And some speakers are more aggressive in delivery as well. Knowing the brand and listening to different speakers and setups could help avoid the typical speaker remorse.
Speakers "Too Big" for room
I have an office with KEF LS50 speakers. I’m gonna try to move in some large Infinity full-range speakers. Typically, conventional wisdom would say that these speakers are too big for the room. I’ll know for sure how they will sound but, why would anyone say that. Why can’t you put large speakers in a small room???