good choice!
as you do not get any stereo imaging anyway I would suggest you build a small preamp circuit with stereo to mono summing plus active crossover. then you can use one amp channel for bass and one for the fullrange speaker(s). "balance" would be used to balance between bass and fullrange.
if you have two fullrange speakers you could direct them in different directions to avoid comb filtering. in this case also consider speaker impedance of parallel or series fullrange speakers and the minimum impedance your amp can drive.
also remember that bass speaker and fullrange speakers require separated air volumes.
not sure what your expectations are, considering there are no TSP parameters and other data for the speakers.
there are plenty of threads here dealing with simulations and measurements of speakers if you want to go deeper into this.