After reading your post, I am not alone.
I have developed a system specs to handle this issue. This solution involved the combination of OneWorld, CLP and RPGLE programs development.
You would need to utilize the DB trigger program to get the correct PDF member from multiple PRINTQUEUES.
Your CLP and RPGLE should automatically create 1 or more history PRINTQUEUE as needed like PRINTQH1, PRINTQH2 to store PDF member files. PRINTQUEUE source file should always have enough room to keep the most recent PDF member. Because once PRINTQUEUE reached its maximum storage, OneWorld batch job will fail. This PDF member management process can be done on nightly basis through the scheduler.
On the OneWorld side, allow user to select and view the PDF as usual but if the PDF member does not exist in the PRINTQUEUE source file, take that user seamlessly to the next history PRINTQH# to bring up the PDF on the screen. It is ideal to create a table and OneWorld program to allow users to define their own PDF preferences setting like how long do you want to keep this report, 30 days, 90 days, 120 days or so on. You can also ask user if they want to save that PDF to a tape after number of days or just simply delete it by the AS/400 server program.
This approach requires you to know CL and RPG ILE languages.