Is there room for the 20W version of the colormax bulb in there?
Java moss has pretty low light requirements.
In my experience, Crypts can take quite a while to get going, then they just take off, packing your tank.
You're right about the BNTs - they get too large for a 6g Hex. If you could grow some HM, or after the moss gets going, I'd suggest pulling the BNTs, adding one or two more Pristellas (or pulling all fish, replacing w/ 6 micro rasbora), then add some cherry shrimp.