I suspect that any of the methods proposed here would be prone to a C&D, but IMO the safest legally would probably be the RSS method (not a lawyer though). Reddit's RSS feeds are public, documented, and available without the need for private APIs, authentication, or an API key, so I don't see how they could claim that a wrapper is unauthorised/illegal. Documenting their private API however seems like a gray area. Google LLC v. Oracle America, Inc. found that APIs are copyrightable, but this use may constitute fair use.
I suspect that any of the methods proposed here would be prone to a C&D, but IMO the safest legally would probably be the RSS method (not a lawyer though). Reddit's RSS feeds are public, documented, and available without the need for private APIs, authentication, or an API key, so I don't see how they could claim that a wrapper is unauthorised/illegal. Documenting their private API however seems like a gray area. Google LLC v. Oracle America, Inc. found that APIs are copyrightable, but this use may constitute fair use.