My advice regarding the construction workers would be to put a large note on the door saying "DO NOT OPEN". Make sure that all the workers know this, and it should be okay.

He'll get over it eventually, but he'll be ticked. He'll try to escape every time you go in or out..so it'll probably be easier to leave him there alone. He won't get as stressed with being without you also. It'll be more like you're on vacation. He'll be mopey, but its better than escaping.