The suggestions you've gotten so far generally appear to be good ones, but you may also wish to have a qualified person check your hitch installation also. From the amount of wear you've described, it sounds to me as though your hitch may also be incorrectly installed - a number of dealers are negligent in that regard. Two different Airstream dealers did a terrible job installing my Reese High Performance Dual Cam Hitch last year, and I finally took my trailer to a non-Airstream dealer who correctly adjusted the hitch.
Reese has good technical assistance via telephone, and thier website @ reeseprod.com also has quite a bit of information.
Here's some pertinent quotes from their website:
What kind of maintenance do I need to do to the weight distributing hitch
WDH and sway controls?
Lubricate the ballmount sockets and spring bar trunnions to prevent rapid wear. When hooking-up, place one drop of oil on the top and a second drop on forward side of upper trunnion. Place a third drop on the rear side of lower trunnion before inserting trunnion into ballmount. Use a heavy oil such as "REESE ON THE BALL". Don't forget to lubricate the hitch ball with one or two drops also. Trunnion should be lubricated each towing day. It is not necessary to unhook the spring bars however, as there are two oil holes in the ballmount top plate for upper trunnion lubrication. Lubricate lower trunnions with one drop at contact point between trunnion and lower socket. Excess oil, dirt, and grit should be wiped out whenever trailer is uncoupled.
Can I grease the Dual Cam Sway Control (DCSC)?
Do not grease the cam and cam arms.
The Dual Cam was designed to use metal-to-metal friction. Heavy greasing of the cam and cam arm surfaces with affect performance. If noise is offensive, a very light coating of lubricant, such as Vaseline, may be used. Tongue weights over 1,200 lbs. may require a light coating of grease to reduce friction and prevent excessive wear. The Dual Cam Sway Control DCSC is not to be lubricated on the cam arms when the tongue weight is under 1,200 lbs. Instead you will want to apply a thin coat of a petroleum jelly, such as Vaseline. This will act as a poor lubricant, but works well to dampen the sound. For trailers with over 1,200 lbs. tongue weight you should apply a couple of drops of an 80/90 gear lube to the cam arm to prevent excessive wear caused by the increased tongue weight.