If avoiding bloodshed is your main concern, then logically the option to support would have been 5/5 instead of 3/5. It's entirely possible that the southern states could have phased out slavery without a Civil War, albeit after some more years (or perhaps even decades).

I don't think so. When Lincoln was elected he had no intention of ending slavery. But what the South wanted was the ability to go into the North and hunt down slaves, penalize and worse anyone assisting slaves, and their normal fair was to take any black men they see even if they were free/ {art pf that was in the Constitution ( another Compromise).

Article IV, Section 2, Clause 3:

No Person held to Service or Labour in one State, under the Laws thereof, escaping into another, shall, in Consequence of any Law or Regulation therein, be discharged from such Service or Labour, but shall be delivered up on Claim of the Party to whom such Service or Labour may be due.

They also wanted all new states to be slave states. Since we had stopped the importation of slaves, the slaves in the US were worth more. At the time of the constitution and I think also at the beginning of the Civil War the greatest asset in the US was slaves. They were biiig money. And listen, it just wasn't new states - they wanted to invade Cuba and make it into a slave state. The sent privateers to Cuba and Nicaragua. The Knights of the Golden circle wanted to make slave states surrounding the Caribe. This was actively talked about. Fifty years before the Civil War the South looked on slavery as a necessary evil. But over the course of fifty years the south convinced itself that slavery was a good thing for the slave, it was beneficial, it was right that whites ruled over and enslaved black who could not take care of themselves. It was a benevolent burden. That wasn't going to change easily at all.