I hadn't even really thought about spills in the trunk until I read this. It makes me think of my current car, a 2009 Dodge Challenger. It has the battery in the trunk, of course it's just a regular 12v battery, but still a spill of a gallon of milk in the trunk could easily cause a bit of a problem if it sloshed over to that side of the trunk and spilled down into the battery compartment.
I'll try to remember to check back here to see if anyone has found some kind of more secure liner with lips around the edges to contain spills. Of course there's also the "cargo net" option as well right? I wonder how much that costs after market?