If you care that much about init just use nosh, s6,runit or daemontools... you don't have unit-files but a similiar short shellscript and some small helper tools, stdout, stderr and respawn behavoir are also very similiar (well systemd was inspired by this). runit also provides good logging capabilities. Socket activation is also possible with these tools and has been for almost 15 years.

Could you eloborate where you had problems? The BSD init system is already quite clean, much cleaner than sysvinit.

I'm not sure what systemd features you need but most if not all can be replaced by small unix tools - that's kind of the point of the BSD philosophy.