In 30 years of tent camping (we're new to the TT world), we only had one ice chest stolen.
The bear dragged it into the woods, took all our left-overs out (tore the hinges off the Igloo 120 qt cooler), and had a feast.
The only thing I lock up to the bumper is our Honda generator & mtn bikes. Everything else (chairs, portable BBQ, misc camp table stuff) is left for the taking. I did install locking clamps on our trailer batteries that sit on the front.
Dave & Tami