An idea I had that would have similar functionality would be to modify the vehicle code to allow existing vehicles to be attached together and also allow for one vehicle to be cut into multiple smaller vehicles.
So in order to make a “vehicle storage bay” build a gantry onto the larger vehicle, then drive the smaller vehicle up to that gantry and connect the two vehicles. Drive to the next town, and disconnect them into mothership and scout craft.
Might be harder to code, but would have added functionality over a dedicated vehicle storage bay.
Alternate alternate idea is to have a towhook that you can attack to a vehicle and use it to tow other vehicles. Could install one on the back of your car to drag a smaller car around, or install one on the front to drag debris cars backward and out of the way.
I also support your idea. These are just some extra ideas.