I own a houseboat with steel pontoons. The boat was lengthened and a section of pontoons added to compensate for the added length/weight. However, too much pontoon for the weight and the boat rides high in the rear. Gear, etc all been shifted to extent possible. So, how can I safely, and without doing long term damage, add ballast inside the new rear section of pontoon to help bring the boat down a bit? I may need to add close to 1k lbs or more.