Etching 1" steel plate to make non-slip surface

I'm proposing to use a steel trench plate for crossing a concrete drainage swale. The top (walking) surface must be slip resistant. What process can be done to the 5'x8' plate?

You could use a two part epoxy with grit mixed in it or spread a grit on it while the paint is still wet. Another option would be to cover it with the anti skid material used for steps. I have seen it in a wide variety of sizes in the past. Only one color-Black.

First of two simultaneous responses --

Or use the 1" plate and tack-weld a sheet of steel checker-plate to it. Assuming you're going to use galvanizing for long life, you could attach the checker-plate first then have the assembly galvanized.

Second of two simultaneous responses --

There are some proprietary paints manufactured for the top surface of wings on aircraft which are anti-slip for use during emergency evacuations. As was stated these are pretty much 2 pack paints with grit (usually pumice) added.
If you do a web search on aircraft walkway paints you will find multiple types and suppliers.

Non skid paint for garage floors is a lot more available and should be considerably cheaper than aircraft paint.