The way the back is outfitted, plywood sheets will fit if you elevate them an inch or so off the ground- fine for thick plywood, can be a problem with fiberboard, thin plywood, drywall, and so on. But honestly if you are doing 50/50, either buy a minivan (e.g. Dodge Caravan with Stow & Go) or buy a passenger something or other and a Ford E-Series beater.
The Metris can do that, but removing the seats gets old fast. I have my seats reversed (front buckets, 3place bench, 2 place bench) to make it easier to open up a lot of hauling room (also because I nap in the middle row) but for plywood hauling... I wouldn't.
I mean if I needed to go do a run for it because I am doing a house project, it will do it just fine. But I'd hate to do that switch regularly.
The most popular vehicle among flea marketeers who only own one vehicle and have a family is the Dodge Caravan/Chrysler T&C- because when unloaded it takes two minutes to convert from cargo to 7-passenger wagon. Despite the fact that they are mechanically crap and wear out fast.