What do you think is a reasonable amount of beauty products to take on a trip of this length?

"Reasonable" is such a loaded word. *g*

I suspect it's one of those things that no-one else can answer for you. It's going to depend on things like how much make-up you wear everyday and how much you vary it, whether there'll be occasions where you want to dress up and be extra glamorous, and also what your packing preferences are -- do you like to travel super-light, or take as much as you possibly can.