Oh its definatly necsesary on mine, but a panel beater i know reckons sand blasting heats up the panels to much and warps them

My sand blaster assures me it will be fine, he said he dosent like soda blasting because of the film it leaves. He says he uses some other abrasive thats not as harsh as the normal sand, so i think i will just go with that idea and leave the van sides like you have in the photos!