Put a liter or half liter soda bottle in a backpack filled with gas and the top screwed on tight. I usually opt for the half liter, but depending on how far you are going to be out you decide. When you hit reserve fill her up head home and switch to reserve when you start running out of gas again. A lot cheaper and I have done this on numerous occasions. This should get you home at least and there is no investment in another tank. Cost $1 to $2! Some might say it is dangerous, but I have never had an issue with it.