I painted the door sills, the inside of the doors inner fenders, inside of fenders and the interior first in the shop. I cut and buffed the interior, the exposed side of the inner fenders and the doors and then assembled the doors to the truck and aligned them. I masked all the surfaces I'd cut and buffed and masked the insides of the fenders too, but I didn't bother to color sand them.
I used a fairly large paint booth so I could spray everything at once. Here's everything outlaid in the booth-
I tried to put everything at a comfortable height for spraying and laid it out in a pattern that I could easily repeat for each coat of clear. I did a couple of dry runs of the pattern to make sure the hose for the gun wouldn't rub anything or catch on a stand and knock it over. We started at the far end of the booth with a full gun and sprayed our way back to the mixing table, took a short break and refilled the gun then started the pattern over again.
You can see I used fender stands, ladders with conduit - basically anything I could find that'd get the parts to comfortable height for spraying.
We used a good Iwata gun with the collapsible plastic bag that holds the paint so you can hold the gun at any angle and it won't drip.
There were two of us in the booth. One person mixed paint and helped with hose control during spraying while the other person sprayed.
We removed all the back taping just as soon as we finished the last coat of clear.
All the individual parts were color sanded, then reassembled back on to the truck, installing welting as we went.