I haven't read the Outlander books in awhile, I stopped after... I can't remember which one mostly because of plot issues that I won't divulge.
But I do remember from the books that Claire's parents were killed and she was raised by an uncle (I think) who was an archeologist who took her out in the field with him. so she was used to roughing it and not having access to electricity and modern conviences. Her first husband was obsessed with Scottish history and his particular lineage, which is why she knows so much about it. And she was a nurse in the field in WWII. So again she is used to doing without or having to deal with more primiative situations.
I think Gabladon did a good job of creating a backstory for Claire where she would be able to take certain things in stride or be used to them.
There was a book that came out - Outlandish Companion I think - where she talked about her process and she did a lot of research. She never even went to Scotland until well after the first (or possibly the second book) was published. And that she set the beginning in post WWII because she didn't want a Claire to deal with a huge technilogical change.