ECVs break down into several pieces, so you don't have to fit all of the
ECV parts together in one place. (Be sure when arranging for your rental that you tell them you need one that comes apart for transport).
A van usually has seats for 7 people, so you will have those seating areas to work with plus the back area behind the seat. If you are able to get an extended wheelbase van (like a Grand Caravan or Grand Voyager), you will have a little longer space behind the back seat. Also, some Chrysler vans have seats called "Stow and Go" seats that fold into the floor to make a flat place where the seat had been. While the seat is up for use, there is a bin that can be used to set some pieces in.