Let us not mince words here. MOST Trump supporters were voting FOR Trump not against Hillary. Trump was not picked by a committee but won his party's primary. Most Trump supporters will vote for whomever's the R on the ballot. Most Trump supporters will never support anything the Democrats do. They're not in play.
Now, on that note if they're not in play and can't be bargained or reasoned with I don't think the Democratic Party should be concerned with alienating or angering that core base and, hell, there's no denying that their core base love doing the same to us.
I think there are times when playing dirty wouldn't necessarily harm us, if Obama somehow got Garland on the court, for instance, the Right would have a hissy fit for sure but I'm not convinced the middle'd care enough to remember 2 years from now, at the least our party's so damaged right now I'm not sure a little bit more fallout from this election would even register. Already our chances for 2018 rely less on our party and more on what Trump does so there's probably little at stake in doing moves like that for now.
But long-term, especially with how you do indeed see the anxiety of white people(sorry guys) playing out I think there's a real danger in thinking of gaming the system too much with ideas like stacking the court with even more justices, something that could just be done each Presidency ad nauseum to no-one's benefit. We should be striving for some kind of stability in our governmental systems because we have no idea where this backlash truly ends.