A few years back 6 of us (essentially all adults 16+) flew into MCO and stayed at the TS side of the World Center Hotel Orlando. IIRC, a got a minivan or SUV from National at no extra cost, as they let you take almost any car off the lot. It was tight with all the luggage but we fit ok. I was lamenting about turning down a convertible offered due to my status!
A week later Hurricane Irene hit NY and our return flights were cancelled with no availability for days. So we had to drive it some 1000 miles straight through. That was a bit cramped but we made it.
I reckon I am saying is to look at National and swipe a minivan at a normal rate. They are usually over populated with them on the lots.