Are you sure the hitch is rated for 500# with the WD hitch? My old SUV was that for weight carrying and 900 (if I recall right) with a WD hitch.
Everything I've ever read is you DO consider the WD hitch as part of the tongue weight. However, the yellow sticker on my camper specifically states the dry weight includes everything that came with the camper, including full propane.
That being said you should be fine. We towed our 17' camper with a mid sized SUV with a straight 6 for years. Traveled all over the east coast with no problems. Yes, I knew the camper was there, but it never struggled.
Just bought a F 150, and can't wait to tow with it an upgrade to a slightly bigger camper. The eb motor is a beast!
Good luck!