Is there a way to set a hidden input on a form with a specific value (not defaultValue, that doesn't work)?
I need it to be in the format '<input type="hidden" name="_next" value="https://mysite.com/thanks.html"/>'
I'm using a third party form submission email website (as my client only has minimal functionality hosting and no website email capability - although wants pro hosting functionality

I know that I can edit the exported html, but, if there's a way, I'd rather do it within the program so that it's retained in the .rsd file in case I forget to re-edit in the event of changes in the future.
Many thanks.