I added four D-rings in the cargo area to help strap down cargo. I bought these D-rings off Amazon and fastened them using M6 socket head cap screws (SHCS) and M6 rivet nuts. Fortunately, we have many of the rivet nut tools at my workplace that are needed to install these rivet nuts, and I was able to borrow the tool and an M6 mandrel over a weekend. If you don’t have access to such a tool, you’ll need to explore alternative options. Whatever you choose, it needs to be installed from the same side as the thing you want to fasten, and can’t require backside access, so solutions such as a bolt and nut will just not work here. Rivet nuts were a pretty ideal solution in my situation.
An important thing to look out for is whether you’re going to be drilling into something important when you drill the mounting holes for these D-rings. There are plenty of tubes and wires running from the rear engine area up to the front of the vehicle, and it would be really easy to puncture one of them if you were careless about where you drill. If you make careful note of where I’ve drilled to install mine, you can match what I’ve done and avoid a problem like this in your Sambar.