In Acrobat Pro you can flatten the form. Look at the Preflight Tool.
It requires scripting and would go under either the submit button action or a button.
Have you considered the Signature field?
You can use the signing to lock the fields and create some additional data within the PDF that can be used to verify that form has has not been changed since it was signed with the digital ID. You will have to have a copy of the public key for the digital signature.