I think that's a great choice to practice on! My only thought is to be careful washing the finished product.
I'm not sure what your methods are regarding hand dying. I recently read a blog post by a woman who does a lot of hand dying and she lets the dyed fabrics sit in clean water for 12 hours before using. She did a massive experiment and found this is the best way to release the excess dye from both hand-dyed and commercially dyed fabric.