That's good news! Thanks for measuring & reporting Claydog. Plywood would do fine up on the closed tailgate, but sheetrock might not like the bend

I guess if you were in that situation you could buy a sheet of plywood to go on the bottom of the stack.
I'm glad my bringing sheetrock home days are over anyway!
You brought up another issue I've been wondering about - what to do with the spare if you need to drive with the tailgate down. I was hoping there was a mechanism to lock the tire into the open position.