When the rear seats are in the up position, is a commercial product available that is strong enough to hold luggage approximately 12” below the roof? It should be long enough to span between the two rear doors. Please refer to the attached picture and note the red arrow above the dogs head. The space above the arrow is where I want the ability to place luggage. When I am driving, my dog is always in the rear passenger compartment and the area above the red arrow is dead space that I would like to use. Thanks for your help!