Pack vertex colors into secondary attibute

Hi! I'm using a very simple shader that only gets the vertex colors from an object, and I would love to have 2 sets of vertex colors to blend between on a single mesh, and seeing as unity only supports 1(! :-() set of vertex colors, I was wondering if it would be possible to, say, export 2 sets of vertex colors from maya and then have the second one be packed into, maybe the normals attribute(seeing as im only using the colors attribute), and thusly blend between the 2. Is this very far fetched ? It would determine the entirety of my production pipeline you see :) Thanks in advance!