What trailer hitch do I order?

I've never sided with the weight police who usually show up on this site, especially, if you're talking about increasing your tow capacity 500 to 1000 pounds, but you're talking about doubling yours. That MH was never made to tow that much weight and there isn't much you can do to change that.

Tow capacity is computed by a combination of weight, hitch, brakes, engine, transmission, cooling system and geometry. You can't just add a bigger hitch and expect to tow anything you want.