I had nothing better to do at lunch so...
Rear hatch - lowest/widest opening 51"
Rear hatch - vertical from headliner to lower jam 35"
Depth from tip of rear headliner to driver's headrest (with front seats moved up a bit and 2nd folded flat) - about 69" (measured the top instead just to insure you clear the glass and wheel well hutches.
Remember you still have to clear another vertical 7" or 8" to clear the rear wheel well hutches once you get the box in. I don't know, man, you can try diagonally to clear the 51" but it still looks tight.
I also copied this to your email.