Sticking to local issues has been the way forward for us ever since the Bush years. Trump's insanity can speak for itself and create a wave scenario all on its own; it's up to the candidates to appeal to their constituents. It's certainly worked in my neck of the woods - Giffords, Kirkpatrick, and Mitchell all stand as proof of that.
+100. As i always say - "district rules!" And Trump will make enough blunders to be not especially popular even in "Trump districts", and thus - will be heavy albatross on Republican candidates. On the contrary - concentration on Trump may give Republican candidates both reasons to defend him (as "unjustly attacked", at least in some cases) AND easy ways to distinguish himself from him if neccessary ("i disagree with my President on ......, but he is still a President, and ....."). And again - don't run "identical" (ideologically) candidates in very different districts: no one is against "bold progressives" in San Francisco, Seattle and many other areas, but it's an absurd to run them in many southern and midwestern disricts (of course - if you want to win, and not just "make the case"). Even Bernie himself ran as gun-rights supporter in mostly rural Vermont, where such position is popular....