The point about fiscal responsibility isn't really about fiscal responsibility, though. It's just another thing to remind voters that they can't trust republicans. And pointing out that past democrats haven't been the radical commies they claimed them to be isn't just about countering the GOP's branding of us; it's also, again, about branding them for what they are: liars.
This branding needs to be aimed at the entire GOP. Not just the person of Trump. It can be framed, initially, in the context of how they are behaving in this election cycle where their candidate is, for the time being, corruptly refusing to leave office. But it goes back long before that. There is tons of ammunition, and it can usually be delivered in short sound bites, without extensive history lessons.
If the democrats have to go on the defensive about "socialism" and "defunding the police," the repugs should have to go on the defensive about their own shit. Disavow the corruption of Donald Trump. Disavow the lies of your own political party. And risk losing your base, or else lose the center. Take advantage of the fact that Trump still has a dedicated base in their party but is broadly unpopular, and likely to be even more so by the time he leaves office. Confront the electorate over the total corruption of the GOP, and force GOP candidates to choose.