overprint issue

[DigitalCrapShoveler]

Yep, not really a way to do it without some sort of PDF editing software, and Illustrator really isn't one of them, unless you plan on doing a total make-over, and even then, you take a lot of unnecessary risks.

It's been mentioned MANY times, even by me earlier... GET PITSTOP. You will wonder how you survived without it after a short time.

[abc]

Easiest way is to try the 30 day free trial, then you can see if it's worth it.
https://www.enfocus.com/en/products/pitstop-pro/get-a-pitstop-pro-trial

If you like it after 30 days you can buy it outright or take a monthly or yearly subscription, i'll let you do the maths on that one.