3, with one strapped to a dolly. this is in a chrysler town and country 2005 with the fold flat seats. I've rented the newer style van and everything should fit the same way.
The trick to loading is first put both cabinets in the back coin door first and use a piece of plywood on top of the glass to make a shelf. load the heads from the inside (wrapped in a blanket) on top of the 2 games. then load the last cabinet strapped to the dolly through the side door, strap it down and put the head on top. done.
you should have enough room for a game that is a bit longer. I've done gottlieb system 80 games which are a bit deeper, but you should have enough floor space.
To answer your question...2 normal length games will fit no problem and room for 4 people. the longer game might knock out one of the seats.
-c
-c