I ran my 93 in brackish/salt for about 150 of it's current 775 hours. I flushed it after every use. I also made the effort or running it in a freshwater lake every 5-10 outings. The risers and manifolds were replaced proactively 1 time. They had some corrosion, but were still functional. I chucked them.
The Mastercraft trailer on the other hand, did not fare as well. Despite flushing the inside after each use, it basically turned into red dust. As much thought that went into the boat manufacturing, the trailer is a very poor design from the standpoint of water contamination and rot from the inside. DO NOT PUT A TUBE TYPE TRAILER IN BRACKISH SALT! EVER. My lesson cost me about $4500.