Slaves as "persons" ("represented"?)

Over the years, I have felt people somewhat exaggerate how pro-slavery the Constitution is and this includes regarding the 3/5 Clause. I spelled out my beliefs some here, particularly that slaves were "persons." My "represented" argument is weaker but think it might work. This sometimes comes off as cheapening the evils of slavery but think carefully understanding situation doesn't do that. This includes constitutional possibilities.

ETA: This also is a case where my various readings led me to have a p.o.v. but citing sources online requires some effort. Would like to learn more about this subject too.