Invisible Status and Silhouette

Is there a way to change the silhouette of the character while invisible?

I can think of one, but I do not know if it will work as intended... my idea is to polymorph the character to the choosen monster and they apply the invisibility spell. Is there a more fancy way to do it?

 

Unless there's a way to change the sprite of a character WITHOUT polymorphing, I doubt it.

 

Thats exactly what I thought... I will need to experiment with what to do first, if polymorphing or invisibility.