It is not that bad, as long as they clean them good
It takes between 45 minutes and an hour for the Sprinters. Maybe 1:30 or 1:45 hours for the big ones.
I have a helper that helps me to line them up and center them on the trucks, while I keep squeegee them in, he cleans the other side or the new truck. We just wipe them down with a 99% alcohol, the truck are already cleaned for us (they power wash them and clean the dirt and grime)
Sprinters get 2' tall and 5' long decals, the big ones are 4' tall and 10' long.