The grades k – 6 was from the Rainbow Resource listing. The Prairie Primer book I have is 2nd edition from 2000 and says grades 3 – 6. Sorry for the misinformation. Some reviewers used it for grade 2. You might wait a few more years before doing something more formal like this.
I checked my records and we used it for grades 1 & 4. We did only the first two books, but enjoyed it. We did not do all the suggestions. We used mostly the discussion questions, Bible (character), and music. We did some hands-on projects and pretended to ride in a conastoga wagon. Some books are oop or outdated, so we used what we had or could find at the library. It was fun. We visited a pioneer village and one room schoolhouse. Several years, we just listened to the next book on audio in the van, without the unit study. This year, we will cover The Long Winter with audio and Prairie Primer unit in December for a 6th grader. We have also used Five in a Row and other unit studies (with CM methods). Have you checked about using those? What did you use last year? What worked about it and what didn’t? What do you like about Charlotte Mason methods?
The audiobook of the Little House series has lively, engaging narration with snippets of fiddle music. We listened to the first half of the books a few years before we used the unit studies. You could do something less formal like that. There are also a coloring book and picture book series of My First Little House.
https://www.rainbowresource.com/prodlist?subject=Library+Builders/18&category=My+First+Little+House+Books/5892
We also listened to music from that time period. We still enjoy listening to them on occasion. It is funny now because my dc thought the lyrics to Old Dan Tucker was “you’re too late for your sucker” (instead of supper). Only a kid would think of candy, right? Here is the music we enjoyed from three CDs:
http://www.laura-ingalls-wilder.com
Scroll way down to the bottom of this list to chapter books and you will see titles for Little House on the Prairie series:
https://simplycharlottemason.com/planning/preschool-guide/preschool-foundations/favorite-read-aloud-books-for-preschoolers/