If it is really a one-time event, any of the reputable Reese or other hitch units and sway bars should be enough to get you 500 miles, assuming you take it very easy, and drive more slowly and with great care. Buying "The Best" for this run seems expensive, especially if you're going to park it and use it as a permanent base somewhere... Brake controller should also be installed and well calibrated, as stopping might be at least as exciting as swaying. Hopefully, you could find someone who has a hitch in your area and would let you use it for a couple days...
If you really want to purchase one, search (use search feature on blue bar above to right..) using words "hitch" and "Reese", and gets lots of advice..
In Theory, there's no difference between Theory and Practice, but in Practice, there is usually a difference...