You're not going that fast when touring regardless of whether you're hauling 70 lbs or 25. So the first thing is fatter tires. What's the point of skinny tires if you're not racing? The fatter tires will be a heck of a lot more comfortable at the speeds you'll be going and will deal much, much better with rough road surfaces. So the OP's bike is not a good choice even with a trailer and a triple conversion. Get a touring bike or use a rigid mtb or even a cross bike but just get something with wide ranging gearing and which can take fat tires and fenders. The pannier/trailer thing is personal choice.