I did reinforce the trailing edge with 3/8" Al tube. Oratex does shrink to the proper tautness, but it doesn't continue to tighten to the point of structural deformation, unless the structure is very thin or weak. You can apply heat right up to just below 482 deg. F., at which point it melts. I just felt good about strengthening the trailing edge.
Here are a few more picture of working on the rudder...