I'm headed out the door, so here's the short version ;)
1. Make sure your trailer tongue is level or slightly tilted downwards.
2. More tongue weight can help, but is tough in a camper.
3. Get a WDH and a sway control bar. It will tow much better and control the swaying.
4. Make sure you are using a proportional brake controller. Hitting the manual brake lever when it wags will help straighten out the wag.
5. Be sure your tires are in good shape and inflated to MAX on the sidewall.
Hope this helps.