Remember, my 5 gallon is a 'heavily' planted aquarium and has been running successfully at this stocking level for 2 years now. The fish I keep are tiny (under one inch) except for the bristlenose and now the two kuhli's. I figure the two kuhli's roughly have the same bioload as the bristlenose so the tank will run well if I remove the growing bristlenose and the juvie head and tail light tetra. But thank you for the advise.

My Eclipse 12 gallon is a tall tank. An Angel wouldn't work forever, but I think it would work for a year or so. A larger tank wouldn't work in my small apartment so that is out of the question. The darters that I have are not a long lived species. In fact, many of the species I keep have only a one - two year anticipated lifespan. Some up to three years. So some overstocking issues become a moot point. I take very good care of my little guys, they are happy, well fed, healthy. My tanks do not suffer illnesses. My longer lived species live full lives, and on occasion I will take one back to the LFS for resale. My dwarf chain loach is over 5 years old now, life expectancy is 7 years tops. My N. Cylindricus are 4+ years, life expectancy is 12 + years, so they are still young.
My oldest betta is 4+ years now and doing very well. So, something is working for me and my fish. I'll have to decide what my 12 gallon looks like after I move some of the overstock in there and decide if I want to keep an angel for a while.