Project Structure --> Adding 'required man days' field

Hi There

I would like to get some feedback or understanding on adding a new field for a project structure called 'Required Man days'. Below is the attach document is where we plan to add the field.

We know it is possible to added the field in however, we like to get this information available view the resource overview tab. Lets say the user put the man days 4 on each of the task, can the resource overview get the information and display it  Attach is resource overview tab.

Like to also check, if there is any existing functionality which we can already use instead of creating this. We want to get enter the required man days for the  task of the project. Hope to hear from you.

Thank you.