@mijostyn , your bass "line array" goes from left wall to right wall, well in theory, and includes the walls as reflectors to extend the virtual length of the array (again in theory and needed for low frequencies). The floor is still a first reflection point, though it barely matters since your subs appear to be working purely below the Schroeder frequency (again, thank you Google!). Thinking of it as a line array is giving you an inaccurate perception of how the bass is behaving in your room or any potential gain advantage beyond room gain.
Talking about late reflections (or early reflections) in bass has little practical relevance. That is not how we hear bass. You cannot decouple how we hear from the acoustics. Also when talking phase, it is important to clarify phase during cross-over so you don't introduce an additional peak or null during transition at the listening position. However, back to Shroeder frequency and real rooms, we are never dealing with single waves with bass, we are dealing with mode dominated spaces. The coordinated arrival of first waves from the various drivers is less critical than how the modal field develops, in the typical room that is not able to damp bass much at these frequencies. That is why bringing the subs out along the walls into the room often works better. The reductions of peaks and valleys from modal excitation is less critical than first arrival phasing which you cannot hear.