Repairing the Door on a Pop Up Camper?

My Palomino Banshee's door slides (on ceiling). It came unstapled (factory staples) and I want to repair the slide so that I can put the door back. What are the best bolts, screws, etc. that I could use to pin the rails be properly. I'm worried that I might go through the top of the roof if I don't get this right.