I prepped the car outide the booth to avoid contamination and had it about 18-20" off the ground on 3 ton jackstands. Below the rock guard you will find a tough composite plastic or foam that is actually pretty tough to sand smooth. I didn't want to risk getting DA sanding "Q's" in the finished paint so I only used 200grit as my coarsest for this section. It was a combination of DA, pneumatic sanding file and the good ole block and about a day to get it all squared up.
"I love deadlines- I like the whooshing sound they make as they fly by"