Need help with adding Bounding box / Trim box to multiple PDF files

We have PDF files that are generated using PHP to send to a printing company. The printing company want us to add Bounding Boxes in these PDFs but with the technologies we're using, there's no way to add them without having the box visible on print paper. Also, since the number of PDFs generated are dynamic, it'll take a lot of work for them to add the Bounding Boxes manually.

I'm new to Adobe Acrobat SDK, does anyone know if there's a way to achieve the following tasks:
1. Loop through each existing PDFs

2. Add / Identify the Bounding Box

3. Save file with newly added Bounding Box

4. Move to the next PDF

The PDFs each have 2 pages, each page is 336.35mm x 226.35 (with 3.175 mm Bleeds - 6.35mm total), Finished size is 330mm x 220mm. Also, assuming if the bounding box is successfully added, will it be visible in printing paper?

Thank you.