@Ketchup Yeah, I remember your gear was quite sturdy lol
I went with the heavy 1/8" steel rod but only used single piece and braced it with foam and packing tape for reinforcement. Basically the bushwacker's gear only heavier, longer, and hinged with rubber bands for suspension. That design was strong and simple, may use it again with a few upgrades.
As far as steel vs aluminum, Aluminum is stronger per pound but it has limitations. If it were a normal model for normal use I could see using aluminum as an advantage but due to the requirements of this challenge I'm not sure it would be best. The main problem is that aluminum has no memory so any harder landings than normal, especially loaded, would tend to tweak the aluminum where the steel would spring back.
Would be interesting to see a head to head set of designs compete in the challenge!