If we stick strictly to what happened at the Constitutional Convention, I don’t see how you get past the Virginia plan. Under the Virginia Plan there were two houses of Congress and states were given seats based on their population. In contrast the Free States advanced the New Jersey Plan under which there was one house of Congress and one state- one vote.
The Electoral College was put in originally not to protect slavery, but rather to protect the Free States.
It was only later as the Slave States became more and more of a population minority that the role of the Electoral College changed and it was viewed increasingly as a mechanism to protect the institution of slavery.
Still, it was only because of the Electoral College that Abraham Lincoln with a minority of the popular vote nonetheless became President with a clear Electoral College victory. The Civil War was ultimately about slavery, but it was set off by Lincoln’s Electoral College victory.
I wonder if it is the electoral college mechanism or the method of determining the number of electors you object to. If the electoral college assigned electors by state proportional to population, would that be less objectionable to you?
The US Constitution’s Electoral College system has withstood the test of time. It has produced Presidents who have had widespread support across the nation and with a large portion but not necessarily a majority of the popular vote. It has proved more decisive and more stable than various purely democratic or pstliamentary systems.