That is exactly what I did in the end, but now it does not validate at all. I can type anything in that field and it will pass.
Aside from that, I did not put the Spry Validations on the page. They simply appeared as I added the WAValidations and the Validation ShowIf. As far as I know, the Spry code appears along with the WAValidation code. There is a SpryValidationText entry for each WAValidation that I added to the page.