Add thickness to clothes after exporting from MD without adding unnecessary geometry?

Before anyone new tries anything I've posted here - I still have a lot to learn. Doing it this way is a lot of work and the project can go South really fast. I'm taking a serious of Zbrush courses today that should shed some light on better methods, or at least shed some light here. At the very least this is super fun and comes closer to some of the cool, time-lapse videos I am seeing. 

I pay for digital tutors which is awesome and totally worth it to get from noob to competent. (Hell of a lot cheaper than Gnomon) Packtpub is another good resource. I still have to hunt for specific stuff and Google is not always helpful there. I went to bed last night with lots of broken meshes and UV maps.