All of the coloured pictures you see are stress analysis done in simscale. The red color is stress over 40,000psi. This is all based on a 50000lb trailer that puts 25000lbs on the tongue and is udergoing a 1.5g braking event. So fairly extreme load case. The first iteration of the design is the one that is most red. Just 1/2 plate bent to fit the frame rails with a bracket at the bottom. Results were not so good as you can see. Then we added some support beams braces back to the frame of the truck which greatly improved the design. This was probably the very best option unfortunately actually getting those beams to fit in real life was going to be a major challenge perhaps almost impossible so we nixed that one too. Then we added a 1/2 inch plate to box out the design and re ran the model and felt the results were adequate. So we emailed the dxf files fro, OnShape of our parts to a large farm in the area that does custom laser cutting and also has a giant press for bending steel. 24hr later we had our parts and were welding everything in place. Some paint and some lights and the projects was done.
Wow, your project turned out amazing! It's incredible how tools like OnShape and SimScale are accessible for free, making such complex tasks achievable. The premier study see this on https://www.koreanpanda.com/ and design iterations are impressive. Thanks for sharing the details and the pictures! 👏🛠️