using PHP to create PDF, without using PHP's FDF functions

Question

Is there any way to create a FDF file within PHP without using the dead FDF functions? I am aware that you can use pdftk to create a PDF from an existing FDF file, but I need to create the FDF file first with one field value set.

Or, is there a way to set one field in a PDF using PHP (skipping the FDF file creation) before allowing a user to download it?

For the heck of it, I tried creating an FDF file in PHP using fopen - did not work. I also know there is a generate_fdf operation within pdftk, but this does not allow me to set a specific value, at least not that I can see.

Does anybody know what an answer could be? I am pretty stuck. Unfortunately, I have no control over telling the client to scrap the full PDF (and instead use a webform).