How much extra design work is needed to let maintainers safely repair an uncrewed ship?
Short answer
Human maintenance access is a basic design requirement, even when no crew lives aboard during normal operations.
Notes
Human access for maintenance remains a design requirement even if a vessel operates without a permanent crew. It belongs in the baseline layout rather than being treated as an extra feature to consider later. Removing the resident crew does not remove the need for maintainers to enter and work aboard the ship. No quantity is given for the extra design effort, and no particular access arrangement is prescribed.