I did something sorta kinda similar on the back half of my truck when I shortened it. I wanted to Z my rear frame 2.5" to gain a few extra inches of drop, so when I cut my 12" section out I left two 3" sections that created extra bracing when I put the two parts of the chassis back together. For added strength, I boxed the frame around the joint. There are much more details in my build thread. My truck has not folded in half, yet.
