I looked into doing that for the platform, but we wanted to be able to sit up and move around while in the vehicle. My wife doesn't like cramped spaces. Lol. It's just the two of us so the seats don't really matter. I still have the ability to take the platform in half and put the seats back in though. The entire platform is bolt in, nothing permanent.
The Thule rack was a cheap pickup, and we needed something weather resistant for an upcoming trip. Works like a champ, but I'm going to take the load bars off and mount to the rack itself. Maybe... I want more permanent boxes up top, I think I may weld some aluminum boxes for that.