Before assuming the alignment is the problem, have your coach weighed in full trim. You might be rear-heavy to the point of changing the front suspension geometry giving you the problems. Your front axle is rated for 5,000 lbs, so if your rear is near max and your front is only at 3,000 or below, that would be the problem. Shift weight forward in the coach to fix the issue.
I learned this the hard way on a Safari 38' DP... With the entire drive train in the rear and the grey and black tanks in the rear, unless I drove with a full 110 gallon complement of water and over a half tank of fuel (110 gallon tank, too), it wandered all over the place. Adding that 900 lbs of water and 350-700 lbs of fuel corrected the issue.