I also have the exact same problem.
The reason I want to create a redirect or “Page” confirmation with my form is to create a custom audience from people that have visited the form page, but not the “Thank you” or redirect page.
In other words, I want to track people who have “bounced” from the form page.
Have you been able to do this with simply using the “text” confirmation? Or have you found a work-around for this issue?