I looked at those cargo pods but bought one of those baskets instead. May not be lockable but it carry more or i can spread the load out across the basket and have a lower surface area, and when its not being used its hanging from the ceiling just above the garage roller door.
It also goes beyond judgement that when we've had the basket sitting on car we've used less fuel (average about a liter) on the open road. I've done more back to back testing then i'd like to throw the basket at.
Our next step is a trailer. Fuel use will go up but with the ability to do more with a trailer, like carrying general crap you don't want in the car (warring kids ?) i think out weighs the extra fuel.