An awful plan? not quite.
There are some very good reasons why dates end up at night. The main ones, IMO, being prep time and scheduling. Most people work during the day, and some, like myself, use the brunch hour to handle business or exercise on days off. Breakfast/brunch dates also leave very little time for preparation (hair, make-up, wardrobe, etc), and assume that the other person is a morning person. Evening dates usually occur at a time when most people aren't doing much; you've already wound down, so you're more relaxed.
Your best bet, as with any new relationship idea, is simply communicate. Let the significant other know what your plans are and see how they feel. Chances are, with enough notice, they will appreciate your adventurousness...or not. thinking outside the relationship box is always a double-edged sword.