I want to sad her cheek and I'm sure it going to eat up a lot of her vinyl cheek to make a nice shape one. The thing is, I open the head cap and see that their vinyl is not too thick and inside is following the cheek shape. I just wondering if I do sanding a lot, will it make a hole in her cheek?

If only I can reshape it rather than sanding....
Also, in the parabox mod website http://parabox.jp/eng_new/custom/how_to_use_knives.html,
it is said that I need to use solvent to make the sanding area smoother. Can I use Mr.Hobby Thinner as the solvent? Or it is too strong for vinyl head?