I like a Coleman stainless cooler for storage inside the vehicle. I can't remember what the interior configuration of the Liberty is but the cooler is an interior trunk if you have room. Put a black towel over it and it should be invisible with those tinted windows. And you might see if some of those interior side panels pop off and what space might be available in there.

For on top of my Honda Element I love my Yakima Loadwarrior. I have a waterproof Yakima bag that fits in it perfectly for trips.

I looked at the 04 LIberty before getting my 04 Element. It was a tough call but since I'm in the city I went with the Element because it is a Honda and the mileage was better (though not a lot).

Good luck!