Sorry to hear about the loss, but stuff like this happens, thanks for reminding us.
I still keep my baggage in the trunk on the day of arrival/departure, but I have nothing of value there anyway. If someone steals my dirty socks, shampoo or replacement pants, so be it. There is too much hassle/cost to store the baggage at a secure location.
I use a bicycle lock to cuff my baggage inside the trunk though, so you cannot simply pull it out even if you manage to open the trunk.
Luckily, being an EU citizen, I don't have to worry about the passport. We also have national ID cards (good for travel too), I take both on my trips, so if my passport gets stolen, I can still travel using the ID card (and vice versa).