I doubt it very much a few enlightened framers believed the 3/5 compromise was a sneaky way to bring abolition to slavery later. This is a specious connection in logic.
The founding fathers based the political mechanisms on non-partisan politics. In other words, each political player was not bound to partisan interests. He could apply whatever knowledge, experience, and wisdom he had acquired beforehand to determine how to cast a vote--or whatever other action the system required of that player.
When the political parties were fully established by 1820, all the "wonderfulness" of the founding fathers' intents was gone.
It's time for the USA to abandon its 18th century social engineering tool and write a new constitution and move into the 21st century.