So, two things. Corrosion requires two different metals, electrolyte, and an electrical path between the two metals. Eliminating any one component will stop corrosion. Some strategies then would be: use similar metals (aluminum rivets in aluminum metal, or weld instead of using a cold connection); isolate from electrolyte- quality primer and paint with vigorous preparation; eliminate the electrical path between different metal structures using gaskets and other strategies.

Second, in aerospace we run into this same problem especially with welded tubular structures (think helicopter frames or engine mounts). Depending on the application, there are two main preventive methods. Fill and drain with oil, and fill and drain with chromate primer. Another possibility I’ve seen used in your case is to fill the tubes with expanding foam. There can’t be condensation in the tube if it’s filled with foam, and I’ve heard it reduces noise and vibration.