Matthew,
Certifiers can still do race day adjustments. This is a case where the "If timing is tight" provision would apply. If you can't get the whole thing (including new map & certificate) written up on race day itself then, on that day, send an email to your Vice Chair, indicating what you've done and pointing out that the new certificate/map will follow. You may then use the date of your email (i.e., race day) as the effective date.