Sterling Silver from POR-15 is a choice for many. It's also a personal choice. I have seen black , and I have seen all shades from grey to metallic silver. Have fun, what you like is what matters most.
I'm getting ready to do the same thing. I've opted for original equipment Massey Ferguson tractor paint called Flint Gray. As with others this is a personal preference which I have used on several applications. You can get this at farm stores as implement paint however the color and quality will not be as good as Massey
If you hitch alone, and use the convex backup mirror system, bright orange is easy to see and people do not trip over it when walking around in the campground after dark. Aluminum Rustoleum is the cheapest and easy to apply. It works but is softer and can be damaged more easily.