Peugeot 301 rear speaker

I want to attach a rear speaker to my 2013 model 301 active vehicle. Does anyone have any suggestions? There is a speaker right now, but he had the owner before me, but his presence and absence is officially. Also, the speaker is in contact with the tensioners of the tailgate. Waiting for your answers considering this, thank you

First of all, welcome to us. slim speaker or original problem, hojam, but if you attach something good, the image will be like this one now.