Well I did cut the lip off so I'll reiforce it some way. I am also planning to put some angle under the bottom lip to spot weld to. Instead of using a flanging tool (which I would think would be hard with the corrigation of the roof), I am going to cut a 2" strip off of the roof section I removed and use it under the butt joint, also spot welded and stich weld the entire joint. I've got some 2"x1/8" angle that I can make a top rail with and can weld the body skin to it for strength. I'm still not sure how i'm gonna make that window you gave me look right. But I think I can use the roof section I removed to make the lower front portion of the bed, (under the window).