"target nearest enemy" can be done by setting the overview to sort by distance, filtering out everything but enemies, and some clever mouse broadcasting. I'm not saying its great, but at least it's doable.

My plan going in was to to target 1 round of enemies (in say a WH PVE encounter) using the distance sort, then use the "selected next" key binds to toggle between those 5-6 that I just locked. Hopefully it can be done in a way that lets me maintain the same targets between all my clients.