Sorry, I'm not on the site here as much as I used to be. We've not gone traveling this year what with the health situation. I have two boxes on the platform On the one side we keep all of our draining equipment, the other side has our wheel locks etc. The important thing is the tongue weight and there are a lot of discussions on it. We found the boxes very useful. All I did was to put the box where I wanted it. I didn't want it to extend out past the trailer wall. Then I just lined up a drill with the holes on the platform. I think I put four holes in the box. I used the appropriate bolt length with washers and tightened them down. They have been there for three years. Our camper is in storage, otherwise I would send you some pictures..