All - One thing no one mentioned and this coach is part of the group, is the steering gear bracket could have serious cracks if it has not had the modification. If you have done the steering bracket modification, then the other posts most likely have it nailed.
First tire wear should show up if this has been going on for a while, check those for abnormal wear patterns. I personally don't think the 500# tongue weight of the trailer would pull that front end up enough to cause this problem, as we are talking about a front end which weighs in at around 12,000 lbs. With your miliage, shocks, or other front suspension parts could also be the culprit.
Where are you? If near Coburg, cummins NW is one place to see, if in SoCal, then Redlands would be my next choice. If someplace else, Freightliner shops have a great track record with lots of MH owners, so you can stop into one of those, I can recommend the one in Tolleson, AZ(SP). Let us know, but if the as mentioned bracket has not been installed, you might have a cracked steering gear box, and it could be the issue.