I had also been thinking about the tying the cage into the frame thing too. I think where you have it tied into the sliders is good because that's thick steel with it's mass spread out over a pretty large area and all of the floor board cross-members tied into that. It may be better to just beef the underside of the body as necessarry as opposed to tying into the frame. On the other hand, tube buggies and such have therir cages tied into the frame and seem to be fine. If going that route though, you might think of ways to allow for some flex, because you know it will, and if it's tied in solid, stuff will start cracking.