I've seen some threads on the Cayman, but as the details are mostly in text, I'm not sure how much they apply to a Boxster S. Does anyone know the best way to access the Soundaktor in the ragtop's version of the trunk? I don't want to go pulling too hard aimlessly on the liner and then not have it fit back.

Thanks!

AFAIK it's the same in the Boxster S (at least it was in my Boxster).
A search of https://www.718forum.com/forum/ should provide all you need--including pics.

The soundaktor is far enough back that it's the same in Cayman / Boxster. On the left side of your trunk where there's a recess (behind the taillight?) there's a small cutout of trim you have to yank free. After that is removed, the soundaktor is accessible by holding back the floor trim.
If none of that helps, it's located on the left wall of the trunk behind some trim - you should only have to remove 1 small piece of carpeting/trim (hint: it's not the floor piece).

Don't be too afraid of yanking on stuff there - techs have to remove a lot of trim pieces just to access the engine compartment so they're designed to be easy (relatively) to remove and re-attach. If a trim piece isn't budging and you're giving it a "lot" of force - you're doing it wrong.

If it's there it should be behind the pulled out bit in pic 1.

You're definitely in the right area - do you own a GTS? The GTS doesn't have the soundaktor as far as I know.

Just found this picture:

(it's the little module on the left in that picture)

Also these:
https://www.718forum.com/forum/86097-post29.html

Yeah, I've been digging through all of the pics and info online, but I don't see it in mine (see posted pictures above). Of course that one you've posted shows a large module on the right as well and I don't see that either. Not sure.