The idea with whitelisting is viable. Use a freehunter+superimportant@gmail.com email for these and then in the classic interface set a filter that will land these mails always in your inbox with an additional label.
Been doing this kind of categorizing with filters since I discovered the feature and never looked back.
>then in the classic interface set a filter that will land these mails always in your inbox with an additional label
I've been using inbox for about a year or two now and this is my biggest complaint - you can't do a lot of poweruser stuff without going back to gmail! Once you set it up, inbox will do it (ex, setting up a filter in gmail filters in inbox as well), but there's no inbox interface of doing it. Other than that, it's great (it used to be relatively slow as well but either I've gotten used to it or they've sped it up).
Been doing this kind of categorizing with filters since I discovered the feature and never looked back.