H-1B Part-time approved, avoid misunderstanding at visa stamping

My US based employer offered me only a part-time position with H1B visa:
25 hours a week for approx. $3,000 a month.

The H1B I-129 petition is already approved.
I am afraid of getting 221(g) during the embassy visa interview simply because of the salary.

What kind of documentation should I bring to prove it’s really a part-time employment and I will never be working for more than 25 hours a week?

I should work 4 days a week, 6 hours a day.

The reason for my hiring is my very deep experience with one of the company’s software project.

On the other hand they don’t want to invest resources for a full-time position into this project at this time.

Part time H1B - Does Less Salary Concern Visa Officer?

There is no need to worry if your petition has already been approved by USCIS.

Visa officers at US embassies abroad are trained to understand these kind of situations.

Your employer would have already submitted the proofs to prove the number of hours you would he working and justify the position and salary.

This salary would have been backed by the ‘prevailing wage rate’ and LCA at your work location in USA.

You cannot really carry anything extra to prove this situation.
If your employer is reputed and they have provided all the petition papers, you should not have any issue in interview