[Mr V]

We have used "Rivnuts" you can often get a disposable tool to insert them for about $2 at your local hardware store. As mentioned McMaster-Carr has better tooling depending on how much you want to spend, the ultimate being the one that works similar to a pop-rivet gun, though we have the cheaper crank style unit that works great. The standard ones to create a ~1/16" gap due to them sitting about that much above the surface. There are also countersunk styles that will sit flush but getting the exact depth of the counter sink could be tricky.

The only downside is that you must keep people from over tightening the fastener that goes into it, go to far and they can start to spin making it very difficult to remove. If properly set it should take a lot of force to cause them to spin since they tighten their grip to a point as the fastener is tightened. For many years automakers used them in thin sheet metal for attaching mirrors and roof racks so they are proven in the long term.