Options for rubrail on fiberglass boat

My boat had rubrails that were buit up layers of hardwood with a strip of stainless screwed on for the rubbing surface. After removing the rotted, splintered, and/or gouged rail, I am now considering my options for replacement. I would like something rugged and not too heavy. The boat is the same as the ones at this link.

http://www.marinesalvagepi.com/26personnel.html

I plan to change the cabin/helm arrangement so that the cabin extends over the location of the existing helm and then move the helm to the back of the cabin. Overall, I plan to keep the appearance more workboat than yatch, but make it nicer than it is now.

The idea that I have now is 1 1/2 inch by 3 1/2 inch rectangular steel tube with relief cuts and welds to make it take the correct shape. This would allow me to weld the stanchions for the handrails directly to the top of the rubrail. Not counting any of the handrail parts, the rubrail would weigh about 300 pounds for about 62' of rail. If I like it, i would redo the whole thing in aluminum someday when my welding equipment and skills are up to the task.

I have also considered imitating the original hardwood with one of the plastic deck lumber products, but they don't seem to be as solid as I would need on their interior, and all of the exposed surface of the finished rail would be cut surfaces.

I haven't found any stock rubrails that would cover the 3 1/2" dimension. If anyone knows of a source for rugged rails of that dimension, I'd consider that option as well.

Waddya think?