Firstly, I'd like to be clear that I'm not trying to detract from Rose's effort. Just to point out that she was the youngest female in a GA Aircraft to circumnavigate Australia solo. Not the youngest pilot to do so.
They both would have had ground support. AWPA and others were meeting Rose along the way, providing food and accommodation etc. And I'm sure, assisting where asked with local knowledge etc re flight plans. And having been on several 25 plus hour flying trips I have always taken every opportunity to check my plans re airspace, terrain, fuel, runways etc with those more experienced than me. Does this mean I wasn't the PIC and that the pilots I chatted to along the way were responsible for those decisions and legs??
The Cessna would have a lot more carrying capacity than the Petrel, and doubt it's overly relevant as to who carried what.
Personally I think they are both remarkable. Huge thing to have carried out successfully. Let alone at such young ages.