If the Liberty had as clean a nose as a 1975 VW Golf/Rabbit (which it does) the forebody flow would be fine
And the flow over the roof is good such that aft-body mods will have a good 'source/onset' flow
The wake is the issue
The wake almost 'tells' us what it wants
Your receiver hitch mounted cargo carrier can be the foundation for a boat tail.You'll be surprised by its effect,even at limited length.
They're kinda like a blow out preventer which minimizes an oil spill behind your JEEP,keeping more fuel in the tank.
