If you stand them on end, you can get 5 or 6 medium size suit cases in the trunk.

For a long trip, I actually am considering a Camry trailer hitch and mounting my Van/SUV cargo pod on a small trailer. It would be low enough to minimally interfere with the slipstream of the car and light enough to only have a small impact on mileage.

http://www.sportutilitytrailers.com/...2TA-TS32SB.htm

If we only put pillows and odd shaped items in the pod, then we'd be talking about just 300 pounds total (the car is rated for 1,000). If you balance that properly, you could get to less than 50 pounds of tongue weight. Easily manageable.