Just scanned the rules and there is nothing about using 2 pieces of iorn to build you front axle, you just can't use aluminium. It should pass tech, as long as it is square and appears to be safe. If it is missaligned, bent, or stressed it probably won't pass tech.
How heavy of material is the c channel? You need to know that becasue I guarantee you will be asked that on race day.
Not trying to bash your build, just trying to pass on info that I have learned over my builds and keep you safe!
Later
Paul