What's generally accepted as the safest way to transport extra fuel? Other than installing an auxiliary tank, of course. I'm going to need to carry somewhere in the neighborhood of 10-15 gallons of fuel beyond the 18 gal. capacity of my tank...so what are my options? I'm not going to be racing or flying off cliffs or climbing vertical walls or anything like that, just driving for a week to ten days between fillups on remote dirt roads for wildlife research jobs, exploring, etc.