I think you have a couple of other options that you could explore. drat is a pretty good and common option for creating a cran-like repository, and it can be set up on a shared network drive. Posit also offers the (paid) Posit Package Manager.
This older thread might also give you some more ideas.
pak would also be a good thing to explore. It generally does a very good job at solving dependencies, so pak::pak("K:/path/to/folder/packageName_x.x.x.tar.gz") should do a better job of installing and resolving dependencies. Are the dependencies of the local packages all on CRAN or are they also local?