I'm a tall player 6'-3" and I play with a 59" cue and hold the cue at the very end on many shots.
I think the standard formula of "length of cue" + "backswing" don't work well for tall players. The reason is the STANCE. My back foot is about 12" past the end of my cue when in my normal stance. So for me, the minimum room size would be "length of cue" + "distance behind cue my foot occupies".
I think when people recommend the table size for the room, they should also account for the stance and height of the player. It is not solely dependent on the length of the stick and the backswing for all players.
Another limitation will be your style of lining up the shot. For instance, I step back from the table and then "step into" the shot. This might require more space again than the standard "length of cue" + "backswing" formula.
I think the best way to find out how much space you really need is to go to the poolhall and measure out where your back foot is on shots, where you stand when you line up shots, and to see if these distances are greater than "length of cue" + "backswing".
Another thing to do is put a peice of tall cardboard reperesenting a wall next to the pooltable at the pool hall. Have someone hold it in the proper place, and see if you can still play comfortably with it there. I think a tall cardboard piece is much better than a piece of tape on the floor in the same location. It will much better represent a wall and the feeling of how much space you really have.