So here is my latest and self-proclaimed "greatest" version"
Naku tells him about her past, her sister, the makeup, Ganpat trying to sell her, Morey, etc. Then she says that she never held anything from Dutta, her heart was always pure...but there is one thing that she needs to confess to. At that point, she should take Dutta's hand, put the "magical" makeup removing cloth in it, and guide his hand to wipe her face. They're hands together will reveal Naku's true roop.
How is that?