There is no solution within your reach for management that is ignorant with respect to your job. Stop putting forth extra effort that will ultimately be wasted. Clearly, you have discovered serendipitously that no one can tell the difference between you doing your job well and you doing your job poorly. So stop trying. Just relax and do the first thing that could possibly work. Really build up some technical debt. Management probably does not even know what that is.
That way, you can use the ever-increasing bogosity of the code base as an argument for being resource constrained. Lobby for junior employees that report directly to you. The end goal is to set yourself up for a job hop into a better position at a better company.
The one you are working for now can be definitively marked as a dead end. So milk them for cash and emotionally disengage. Get your spiritual fulfillment by investing your creative talent elsewhere. Meanwhile, coast until you can bail out safely.
That's about what I'm doing at my crappy, soul-crushing job.