Salut Tom,

As I understand it "bivouaquer" has a sense more of a "temporary camp".

The lesson makes reference to the Germans setting up camp in a war situation  --  I suspect that they planned to stay for a while at least. 

This is why I'm not sure that "bivouaquer" is appropriate in the context of the lesson.

https://www.bivouak-paris.com/blogs/actualite-cosmetique-soin-homme-bio/le-bivouac-quest-ce-que-cest

Let's see what others may comment.

Bonne journée

Jim