I've got a few years on me, much of it as a Dem, then a long indie hiatus, and now just returned Dem due to Trump. My "libertarian-left" lean is the closest the forum has to me likely being mostly a social democrat, in politically terms. And yes, I like Bernie. I'm actually fairly conservative in how I conduct my personal and family life, however.
But I greatly enjoy political analysis & strategizing, so not all my posts are about my specific desires or ideology. My posts here now to you, are a bit of both analysis & desire.
I do believe the Dems indeed need to move to secure the border. And I believe it will not cost them much with their base. They can still fight for DACA, which I believe is the right thing to do, and they can also argue immigration policy that differs from the GOP. But they've got to get off with supporting illegal things related to immigration. I don't see illegality issues as being winners, besides the basic fact that illegality is not right.
Wedge or not, I don't see arguing for illegal immigration working for them going forward. There's plenty of legit wedge issues they can find with Trump these days, if they so chose.