Not sure how the category rules apply here, as there isn't a "green boss" at the end of this game? Just the big pig monster thing that the vinyl skinsuit wearing lady turns into, though that might be a difference in ports of the game. I wasn't sure how to time it though, so here is how I did it:

I commit to One Player and start the game at 6:02. The head of the final boss explodes at 51:01 prompting the "CONGRATULATIONS" message to appear signaling the end of the game. Calculated time: 44:59.

(Alexa, play "Rag Doll".)