Yeah the back cloak you can use the bard and scale it to make it longer, or the romeo cloak, both work very well.

Another Idea would be to use Rubio's sheet, tho his site has been down for eons now, which is really really sad.   The sheet can be used to volumize gowns, add more "umph" to cloaks and so fourth, and works well on its own scaled and moved around.

I'd forgotten about the romeo cloak, that'll work

if all you want is white, or a color, just go into materials and remove the texture, and in the color box, just add the color you want and play with the highlight and reflections as needed :)

P.S. If you have experience in the cloth room, making either cloak dynamic really helps