According to the N-400 instructions (mirror), section "Required Evidence", under "Below is a list of documents to bring with you to your Form N-400 interview.", item 7E (on page 12-13), you need to bring that evidence with you to the interview. It does not say that you need to submit it with your N-400 application.
Item 7E (on page 12-13):
E. Trips Outside the United States. Bring evidence that you maintained your continuous residence in the United
States if you have taken any trips outside the United States that lasted more than 6 months but less than 1 year.
You may submit documentation which includes, but is not limited to, evidence that during the absence:
You did not terminate your employment in the United States or work overseas;
Your immediate family remained in the United States; or
You retained full access to your place of residence in the United States.
- An IRS tax return transcript or an IRS-certified tax return listing tax information relevant to your absence for
the last 5 years (or 3 years if you are applying on the basis of marriage to a U.S. citizen);
- Rent or mortgage payments and pay statements;
- Bank, credit card, and loan statements showing regular transactions;
- Proof of car registration and insurance;
- A photocopy of your passport showing entry and exit stamps; or
- Any other document that shows you have not abandoned your residence in the United States