One solution could be to add a `build` and `install` field to the dependency in the project's manifest, I'll see with the feedback if this is worth implementing.

For now, you simply have to add a `shipp.json` file. For SDL I have a repository `shipp-pkg-sdl` (not yet published) which contains only the `shipp.json` file and a submodule to the latest release. It's not perfect, but it works well for now :)