TCPBurban

Hello, I am new to the forum and just got this new 2016 suburban. So far so good. I only have 2 issues, charging ports don't have power when ignition is off and the sound system really sucks. No speakers on the back? Last gm suv I had was a 2000 tahoe limited and I also had a 99 Yukon Denali, although they didn't have 3rd row they had awesome stock sound systems with speakers all the way to by rear tailgate. I know I only have an LS, but shame on gm for not thinking about 3rd row passengers! Anyways, does anyone know if I can simply add the speakers somewhere in the rear? Precut holes?