My cross bike is a "virtual" 1x9, as I basically tool around almost exclusively on the middle ring of my Ultegra 52-42-30.... I have a 12-27 on the rear. The only time I get any rubbing/chainline issues is when I'm on the largest cog. Around here (SW Idaho) that's not often.

I'd recommend a 42 or 44-tooth chainring and a 12-27 based on my experience. You can get up all but the steepest climbs (without being Lance) and can still top 30 mph without spinning out.

You've got the seed of a great idea. Go for it!