Not sure about the hump but here's a thread with some people discussing it ...
Sleeping comfortably in a 2017 4Runner
... seems like there's a "slight tilt" but that the hump isn't felt at all.
I went with QTY 2 80"x24"x3" thick foam pieces from Home Depot which were $30 each. I cut them down to the right length and it still left me with room to store stuff on the driver side. Throw a sleeping pad and a sleeping bag on top and it was perfect for me! Wouldn't work for 2 people but for one person it was great!