The trimout (finishing the marriage line in a doublewide plus taking care of any defects) may be done by a factory crew or the dealer. It is important to know which so you know who is responsible in the case of problems.
In some parts of the country where it gets very hot -Houston, TX for example - the trimout may be done at night using flood lights. Sometimes homeowners are actually asked to sign the checkoff list after a night time inspection.
You want to make VERY sure you do in fact agree that the trimput is complete! Once you sign the paperwork accepting the job you have little leverage if you later discover there are problems. This is one of those situations where you must not give in to your desire please and be prepared to insist on a quality job.