Having your freezer in a space that is relatively cool and shady, such as in the house, in a basement or well insulated garage will keep it from working too hard. If it's half or more empty, put some jugs of water in there. They will help it stay cold longer, plus they are free cooler ice for excursions. I suppose you could put a piece of styrofoam on top of it, or even drape and insulated blanket or sleeping bag over it, just don't cover the compressor area in the back which might make it over heat.