In years past, folks with class c motor homes (those built on a van front, 1 ton chassis) had limited gas capacity--I believe 36 gallons--and driving a Dodge 440 was about 10-12 miles per gallon. Anyway, the bumper on these rigs is a lightweight steel square tube. I think they made it a tad deeper--but at 8' in length, it held another 10 +/- gallons, which had to be transferred to the main tank with a small electric fuel pump. that sort of arrangement could be made on the Patriot to give another 5 gallons, I think...
But now we have all sorts of emmissions and air quality issues to content with. My advice is similiar to what Senator Huey Long said about voting: "vote early and vote often!" Fill up when you're 1/2 full instead of running on E....
And by the way, my Pat. low fuel light comes on and says I have 33 miles to go, if I slow down, I can get that number up to 40. But once it drops below 30, it just shows the low fuel symbol.