I haven’t measured it but one of my test during my car shopping was laying down in the back. I’m 5’9” and fit. At your height you would either need to pull the back seat all they way forward and fill in the canyon it creates, or make an extension. There’s a guy on YouTube that has his PP setup for over landing and he shows what he did. Essentially, a piece of plywood he secures to the passenger seat headrest with rope. I’ll post a link later if I can find the video.