When my wife was preggers with our first daughter, we went to Costco and signed up. Like dolts, we took the Boxster.
We bought diapers, wipes, (A whole lot of diapers and wipes. We thought it would last a while - Oh how naive we were.....) We also bought a bunch of other stuff - it was our first visit after all.
So anyway - we walk out to the Boxster with our "flatbed" cart full of stuff. Just about the time we get to the car, we look at each other and realize - ah-oh, we have the convertible, not the wagon.
We proceed to unbox all of our purchases. We stuffed things all over the place. Behind the seats, under the seats, on the sides of the seats, in both trunks, behind the spare tire, in the little spaces on either side of the battery, under my wife's feet and legs and on her lap (such as it was, being like 8 mos preggers) I even had stuff that we could secure while driving under my legs.
I am sure we amused the heck out of other shoppers (and ourselves). We made it home just fine.
We were astonished how much stuff we were able to fit in the Boxster.
Although not recommended, it was an acceptable (or at least workable) Costco hauler.