I did the same thing on mine a few months back. The only difference is I used hex button head bolts. An allen wrench is needed to remove them.Here's my low cost solution. It will deter an "opportunist", but a real thief will take what he wants. I suggest a shoulder bolt instead of the full threaded pictured, as it's easier on the rubber grommet. The spring clip and "U" bolt both just slip on/off. I only use 1 per side.