even the carbon driveshafts in the newer trucks are this thin aluminum on the inside. and the carbon doesnt do very much as far as makign them stronger. you should see what happens to these on 39.5 inch tires. bad idea.
steel is the way to go on a stock or 4x4 truck. you can get thicker race aluminum driveshafts but if corrosion is an issue, i wouldnt bother.
i live a block away from the bay. i know all about corrosion.