Huh... The Part 15 sites seem to be loosing traction, but there seems to be more Part 15 stuff here,
https://www.antiqueradios.com/forums/index.php They are mainly doing Part 15 AM transmitters for something that classic rigs can jam to, but could certainly be used for our purposes.
And, forgot that Part15.us went to part15.org, but that even seems desolate.
https://part15.org/