This is a fascinating topic. By my rough calculation, if you're only off by 1/2 inch in a width of about 8 feet (96 inches), we're talking about a 1/2 percent grade. This is well within the comfort level for camping, the operating level of RV fridges, and probably hard for the average person to even notice if he/she wasn't specifically looking for it. Since leaf spring spacers on one side are only jacking up one corner, does this tend to have any torquing effect on the chassis, however minute it might be? I assume that there are not also coil spring spacers on the left front, but maybe there are?? I guess I'm asking what bad effect results from disregarding a difference as small as 1/2 inch whether it's caused by adding a spacer or not adding one? Also, wouldn't you have to measure the side clearances in a variety of situations and loads to determine the full range of the problem? In other words, if your motto is if it ain't broke, don't fix it, is being off level this much "broke"?