It has to go in the top.
The good news is the lid to the main box can be lifted up with the tent deployed or closed.
Take care when closing it back up, though. It is possible to jam the aluminum plates on the underside of the tent platform that slide together when it is open. ;-)
The tailgate opening is 32"W x 16"H
37qt ARB is (H16.9” x W15” x D27.8”) Almost:Wow1: