Gluing on aluminium checker plate

Automotive body panel adhesive. I redid the wheel wells on the truck with a panel and that's all that holds them on. Only trick is working out a way to apply pressure while it cures. On the truck, I used boards and nylon ratchet straps but that probably won't work well on a flat surface but a piece of plywood and some bars for securing loads in a truck bed that can be twisted tight. Then just park next to a brick wall or other solid structure and twist the tight to hold it tight until it cures.

With no holes, you don't have to worry about water intrusion. You could do the edge with silcone but not really necessary if you get a tight fit.