Diesel at $3.23 today makes me feel better, at least. Still .60 more than low grade gas.
I have never (in 12 years) felt the need for an aux tank. If I am running really low and the advertised price is more than seems reasonable, I stop and put $20 worth in, Sure it is only 5 or 6 gallons, but at 10mpg with the trailer on it gets me to someplace with more reasonable prices. The only exception was to and from Alaska when I filled as soon as it went below half, no matter what the price. Petro Canada loves me, this I know.