Others should chime in here and correct me, but if you add wheel spacers you are changing the offset and possibly hastening bearing wear. If the rubbing is on the upper dust cover (tube) simply cut it off each shock. I removed mine per another forum member's recommendation to clear the slide out mechanism, but it would serve the same purpose for you. Look also at the possibility of relocating the upper shock mount slightly. I welded some 1/4 " flat steel to the top shock mount to give me another 1/2 inch clearance.
1999 F250 w/7.3L Diesel
2014 Silhouette 299RKDS
Nights Camped 2016 - 21
He who dies with the most tools, wins!