The best temporary fuel tank that I've used in the past are boat fuel cans. The tank can be removed when not in use by simply twisting the fuel line, (quick disconnect). Some tanks have a primer bulb that you can prime the fuel up to the fuel pump. Works good to keep from running the battery down from running the starter to draw fuel up to the carb. The old steel boat tanks work the best, but finding one that is clean is a bit of a chore. Plastic will work, but be careful filling it in the Jeep. Plastic has a nasty habit of creating static electricity, causing a potential fire hazard. Not real likely, but could happen.