Wheel Spacers ???

If you were to use wheel spacers, then the wheels may not contact the centering ring on the rotors. I suppose it wouldn't matter if there aren't any centering rings, but it certainly wouldn't be good for your bearings. Or if your wheel studs don't have extra length to them, your going to have less threads holding the nut to the stud. Personally I'd suggest finding wheels with different offset/ backspacing. Wheel spacers have always seemed iffy to me, especially on something as heavy as a MH, it would be catastrophic loosing a wheel going down the highway.

If your having wandering problems, perhaps look into aftermarket sway bars, and other suspension modifications for your particular suspension. The PO on mine put helper airbags up front and a huge rear sway bar, and said the difference in handling was incredible. It certainly doesn't sway as much as other MH's I've driven. Also if you haven't already, be sure to check the condition of all the suspension and steering components one worn pin or joint is all it takes. Perhaps go to a different shop and get a second opinion on an alignment. I've been to different places that have told me different specs on alignments. Not sure why different shops have different specs, but it might be worth a shot. Good luck