Wandering can be caused by having too little weight on your front axle. Most RV's will handle better if the front axle is loaded close to the maximum weight allowed per your placard.
Try shifting some of your load around and see if you can get a little more weight on your front axle. Weight BEHIND your rear axle tends to lighten your front axle. Move those items forward if you can. Check to see what happens if your fresh water tank is full or empty, as far as front axle weight is concerned.
Obviously the best thing to do would be to at least get both axle weights in lieu of a 4 corner weight.
