Fixing navigation of multiple StaticMesh-based characters


I would like to post here a link to my UE Answer Hub question:
I have already got an immense amount of advice and feedback from amazing people on Answer Hub, but the time I have to complete the game passes by while I am stuck because of the issues presented in the question linked above. I thought that presenting the issue to those of you who do not use AnswerHub very often may really help me find the most adequate solution. Do you have any ideas?