Is C of O totally necessary?

[Account Closed]

So I converted primary into a rental, and figured I needed a rental dwelling permit. The town came by to inspect the home, found its in great shape. Problem is, to meet “code” it needs an egress window installed (~$5k), backwater check valve installed (~$2k), and electrical inspection, as the basement is finished. The costs and scheduling estimates and work to be done has been a complete nightmare to where I’ve considered selling this perfectly fine house. So is the C of O even entirely necessary? Also, for plumbing issue it’s a full day of work and tenants wish to be home while it’s being done. Do you allow contractor to do work while nobody is home?