Okay, I texted with HPI who makes the product for Summit. See the attached photo for their recommendation if you have a shortened frame. I added the red marks where I intend to weld 1 inch sections to secure that portion of the channel to the frame once I have it completely test fit and centered. That c-channel is designed to slide in/out to be able to center the entire assembly within the frame rails. I might see how stiff it is and if, okay I may not weld that section just to make sure I don't screw something up. I'll post some photos when I get it mocked up and modified.