I'd have thought it possible to get a couple of helmets in the front, trouble is it's a lift off the bonnet job.
which looks like a two man job from what I have seen on youtube. As far as securing the helmets in the back, I would assume someone could always run a bike chain or something likewise in a wire form through the helmets and into the frame which would at least deter a quick getaway with such items. The same could be used for the steering wheel and those that had the tonneau cover could cover up the passenger compartment to at least somewhat deter bystanders from sitting in and or taking things when you are in a store or otherwise.
