I was wondering if you were planning to add paintable thickness at some point?
I have worked with other cloth solutions before that had this features and it was quite useful.
Unfortunately, painting thickness is a feature that we will most likely not be able to develop any time soon as there are
a lot of unwanted side-effects.
If you are trying to paint thickness to emulate a second layer of Cloth, you could instead try to create and simulate the actual second layer of Cloth.
Carbon is highly optimized and adding a second layer is likely not going to drastically impact your performance.