Larger 2015 Jeep Grand Cherokee Fuel Tank

I doubt it is possible. A couple of 5 gallon cans will extend your range considerably.

I found a company called LRA (Long Range Automotive) out of Australia that has an auxiliary tank for the Jeep Grand Cherokee. It may or may not fit depending on what receiver mount you have. The factory one should be fine but there is a company in my state (WA) that is double checking with the manufacturer. They are a little expensive though.