I am looking for an optimum procedure for color correcting footage from multiple cameras in Vegas Pro 8 so that they match. Is there a better approach than just eyeballing?

Get on one of the corrected camera's footage and take a snapshot to the clipboard.

Now start adjusting the other camera and turn on "Split Screen" view. Click the little down arrow beside that button and choose "clipboard". Now you can see both cameras footage at the same time to help match them.