I mean you want to set up boundaries between chun and boxing. But other that a vague feeling of wanting to. Nobody has a suggested a method of doing that.
---Why do you think there needs to be boundaries? Rackemann doesn't seem to place any boundary between Wing Chun and boxing. He seems to blend them together pretty well. And he says that he no longer teaches the forms. He starts by teaching solid boxing base and then teaches the Wing Chun "sau's", Chi Sau, and various drills. Mark Phillips is essentially boxing at range while also including some Wing Chun defensive hands and then flowing smoothly into "standard" Wing Chun at close range. I don't think a boundary is needed or desirable.
There does not even seem to be a plan as to what you want boxing to do for chun.
---I guess any "plan" would be to make Wing Chun more functional in a modern fighting/sparring environment. To "update" or "evolve" Wing Chun somewhat. Now this wouldn't be for everyone! I would certainly not want to see "classical" Wing Chun go away! And obviously people are already doing this whether they truly acknowledge it or not. It seems there are a lot of people out there that are doing "classical Wing Chun" but then resort to some very "boxing-like" structures and methods when sparring, whether they are doing it on purpose or not! At least that what it looks like in a whole lot of Wing Chun sparring footage that is posted!

And some here have already admitted that this is true.