There's not much coverage about the aftermath of incidents where lethal force is used against property crimes. I'd like to see some anecdotes, but I believe that the cost for lawyers and civil penalties would make even the loss of a nice truck seem insignificant.
Cultivate a mindset that use of a firearm is ONLY in the event of a threat to life. Even as the OP indicated, showing a weapon to intimidate the thief, is generally considered a crime.
It is my belief that any time you shoot somebody, justified or not, you will get sued. No big deal: Anyone can sue anyone for anything. However, you need to show that you acted reasonably, that there was a credible threat against your safety.
In considering these scenarios, make your plan to prevent the theft, but do not use a firearm for anything except reacting to a threat against your personal safety.
Remember that we are the good guys, and we play by the rules. We win in the end.