for 12k watts you are gonna need more than one run of 1/0 to the back i would tihnk and more than one HO alt and prob a few more batts right??
I am planning on going with 2 VFL's 500.1's and 4-6 batts in the back with a pair of 250amp alts or a 300amp alt if that will be enough. 4 18's blowthrough and prob 4-6 runs of 1/0 to the back