I've been digging into this a bit more and am wondering if the getCMSValidator can handle complex rules or if it's just checking for a value. I looked through the validator class and it looks like it's just looking for any value. I know the EmailField has additional validation so I'll poke around there as a starting point to additional validation on a form field, but wanted to raise the question. I know in things like the CsvBulkLoader you can pass to functions for verification/object requests. Probably unrelated but would be cool to be able to have array('FieldName' => '->fieldValidationCheck') to set up perimeters.