Adding a bit more ...
The usethis package has some basic support for non-package projects in the CRAN version, such as create_project().
Context: usethis is one of the packages created in the Great Devtools Diaspora. It is the primary home for workflow functions, for example, the functions to create a package or project or to add specific files or features during development, like adding test infrastructure or using Git/GitHub.
A new release is imminent (check out the dev version on GitHub) and non-package support has increased moderately. But it's still limited to fairly mechanical operations, initiated by the developer.
The release after that is likely to include opinionated support for a specific analytical workflow and directory structure. More in the tradition of, say Project Template (but quite different).