That deals a lot with theory, I am in need of some implementations that work. I've found things that don't work, but I need something I can start and play with.

Nothing really seems available which seems sad.

UVM, the virtual memory subsystem in BSDs, is actually very nicely explained in Charles Cranor's disertation. An abridged version was presented at USENIX: https://www.usenix.org/legacy/event/usenix99/full_papers/cra... , and if you google around, you can find the full thesis.

So I would look around unikernels like IncludeOS. They might have something from linux ready-to-use.