I thought that newbies and shoppers might be interested in how we increased the storage in our Sprinter. I'm not claiming that these are the "only" or "best" solutions but they have worked for us. I...
To keep bottles from tipping over when our food cabinet is not all the way full, I put them in empty plastic jars - peanutbutter, juice bottles etc - which have been cut down to a couple of inches high.
The jars are kept in place with the museum/earthquake "silly putty" available in hardware stores. I can easily replace them with different sizes as needed. The plastic jars do a great job of keeping things upright.
Plastic jars can also be used to hold glass drinking glasses in place.