I wanted to make something that resembled Auratone in regards to a reference single driver, that wouldn’t suffer from crossover issues, but not sound as crappy.
I don’t plan on making a stereo pair, just a single central mono monitor.
Your goals are conflicting with each other. Single driver designs inherently have a lot of problems which cause crappy sound, and listening in mono actually reveals more flaws than listening in stereo.
If you want the appearance of a single driver, but without many compromises, you could just buy a single KEF Q150 for $230.
A slight bit of EQ or a crossover mod and you have a great speaker for monitoring work in a music mixing/mastering scenario. Building a better crossover would probably only cost about $75, and that includes using high quality air core inductors.