Get yourself a rattlesnake. A big mean old diamond-back. Get a really expensive looking briefcase and put the snake in there. Leave it right on the front seat. A would be theif won't be able to resist. You'll totally know if someone breaks in.
Really if 1 out of 20 of you mooks is clean and sober a year from now it'll be beating the odds. Figure 90% of them are just trying to dodge a case or just get their muscle back while they save up enough money for their next run. Those people are not A1 credit ratings, most won't make employee of the month, and many will be dead or incarcerated within 6 months. If I were living someplace sketchy, I'd have all my stuff that I couldn't afford to lose at a friend's house or somewhere safe.