Larger gas tank

I have the same problem, but have just adapted the policy of refueling once the gauge hits the halfway mark. I can usually time it with a stop for lunch or a pit stop. And, it's why I try to shoot for no more than 300 miles per day when traveling. But, since we're retired, there's no reason for us to be in a big rush.

From what I've seen, even if you can replace the tank, it will be an expensive proposition unless you have the skills to do it yourself.