What? Jesus. You can get 1TB hard drives for £65! And yes, you can install to NAND. You say you the premium Wii U with 32gb NAND, then install to NAND - at least for this one game.
Have you even read this thread? I have tried to install to NAND more then twice and with and without the RedNAND but it just fails?
And no, I will probably not pay $70 for a harddrive if Im not first sure if this will work.
If it is supose to work to install to NAND the way I have stated that I have tried, then there is probably some other problems more then not able to write to HD.