Board Thread:Theories and Speculation/@comment-25549954-20150524070831/@comment-945885-20150524105056

Shikamaru Hiden states that Naruto's Six Paths Sage Mode was possible because he had Kurama and the other eight Biju sealed in him at the time, which effectively made him Ten Tails' Jinchuriki. As he only has a fraction of their chakra in him now, he only has a fragment of the Sage of Six Paths' power.

I believe that what we see in Gaiden is just Kurama Chakra Mode. I think it's worth considering that the markings on his body change as a result of his clothing.