I worried about the same thing about sending something that exposed my Social Security Number. So I submitted my driver's license and car insurance policy for identity and residence respectively. (It was kind of a pain to find a proof of residence they accepted since I had no bills in my name.)

For anyone browsing the thread, this is part of an email their support desk sent me for accepted documents, which is significantly more permissive than the upload page for verification suggests:

    1 A copy of your government issued photo ID such as:
    - Passport
    - Permanent residence card
    - Driver’s license

    2. Proof of Residence that is not older than 3 months such as:
    - Monthly utility bill
    - Internet Bill
    - Cellphone Bill
    - Tax Return document
    - Residency Certificate
    - Voting registration form
    - Medical insurance
    - Pay Slip
    - Car Insurance Policy
    - Medical Bill