The answer is going to vary by the carto, the number of holes, and the juice itself.
I'm also a PG-Free vaper.
I've tried 3 brands of cartos so far: Boge, Smoktech, and Ikenvape. Smoktech has much looser filling than the other two. I started with 3 hole smoktech, then moved down two, than one hole - and even with a fairly thick juice they were all floodsville and I threw them in the garbage (your experience may vary.)
The boge cartos wicked my thicker juices fairly well. The Ikenvape has similar amount of filler to these so they're about the same. Especially if you are using the flange type, your VG life will go much better if you get a needle tip and inject the first fill of juice right into the filler instead of the other methods (your experience may vary.)
Finally, some PG-Free (as opposed to '100% VG' because that would mean no flavoring) vendors work to make their juices a reasonable consistency for cartomizers so you won't have any problems - in my experience, this has meant Velvet Cloud Vapor, and Virgin Vapor. Both are not syrupy-thick, but have no PG. I know VCV uses some distilled water, not sure about VV because I didn't like the taste anyway.