You may want to use steel, instead of aluminum. Aluminum is lighter, but it has a tendency to stick to rocks. In fact, they use aluminum for the grips in some wading boots. I found out about this when I had an aluminum drift boat and had to keep a coating (Gluvit) on it to keep it from hanging up on the rocks.
Of course, you could use Aluminum and coat it with Gluvit, but I would be a lot cheaper to just use steel.
Meach4x4