Definitely get an alignment done by a reputable truck alignment shop. Then, load the coach like you are heading out for travel, get all four corners weighed, and move the stuff around to get the right and left sides of each axle fairly even. Set the tire pressures as recommended by your tire manufacturer for the weight your are carrying. Then, if you still have some wander introduced by side winds or by 18-wheeler bow waves, install a rear trac bar to keep the coach box and the frame moving in the same direction at the same time.