I have looked into this. COLLISION was cool enough to snap off some pics of his K5 frame w/ no rear half of the body to how how it mounts.
Im sure it can be done, but having the body off would be a huge help to get in there and cut and weld. I havent ruled it out yet, I may still do it as it will put the tank close to even w/ the rails and the hitch could also be lifted for better departure angle.