Hey, I also have one of my guitars tuned in fifth ~like a cello From low to high CGDAAe, with custom gauge strings to match the neck tension. One A is wound, the other is full...
CGDAEE. I like the ringing unison of the highest E. I also have a piecemeal set of strings for tensions as well, starting with what I think is a .062 for the low C, and a .010 for the high Es.