I guess we'll just have to agree to disagree on whether this is a bug or a feature.The issue is not that PCs can die, the issue is that the module designers were totally silent on it....
Amend my previous comment to "I'm glad you found a way to make it work for your group," then.When I took over, I basically used the adventure sites as location pieces. I changed practically everything else (I kept the cult, but drastically changed how the PCs interacted with them) and threw in a bunch more stuff (i.e. other places to adventures and other NPCs/monsters to meet). It's all good.
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Also, to answer my own question about the map, with a little digging, I found this:
http://theredepic.bigcartel.com/product/overland-map-dm-player-digital-download-versions
I'd even bought that map pack, but hadn't studied it in detail yet. It shows the crashed castle at...could that be Oyaviggoton??