I missed them; don’t recall hearing about them even at the time.
Sorry, but no, not even close. Maybe all you know about the topic is maybe what you picked up in grade school or something (probably with some deficient textbook for how wrong you are about it), but at the time in question the vast majority of the world knew that slavery was wrong and immoral. If you “guarantee” that anyone living back then would have supported slavery then how do you explain all the people who didn’t: the North, the Underground Railroad, the abolitionists and all the other countries in the world at the time? The only people who supported slavery were a few influential people in the Deep South, based upon ugly religious beliefs (the ignorant masses) and economics (wealthy landowners who didn’t want to have to hire workers and could just buy them outright). And the issue was important enough that the country split in two over it and caused a massive (maybe you heard of it?) civil war.
So much for your “guarantee.”