I did a video on this subject for my van a few month back we used 4140 chromoly steal. Itís Stronger then aluminum , Bounces off rocks better, and is just as lite. please check it out it might help you with your challenge.
ďBuild something coolĒ on YouTube here is the link to the video
I have to admit I can watch that type of video all day long as the technology these days is something to be admired.
If I was 40 years younger I would be all over trying to be in a profession that intergrated CNC controls.