When the road is too narrow for two lanes of traffic and two bicycle lanes, do what they do in parts of England, Scotland, Switzerland and the U.S.: take out the centre line and make one oversize lane for both directions of motor traffic, flanked by two bicycle lanes.
Centre-line removal is discussed in the recent newsletter from the U.S.-based bicycle advocacy group, One Street. The resulting roadway has a centre lane, much like a mutual turn lane, flanked by two dashed-line bicycle lanes. When oncoming motor traffic approaches, vehicles yield to bicycles in the bike lanes, or, if the lanes are empty, use the lanes to augment their space. The result is slower speeds and accident reduction.
The lanes are called "suggestion" lanes or "advisory" lanes (defined here) and appear to be intended for low-traffic residential or feeder lanes. The traffic volumes that I see on Block Line Road in Kitchener, for instance, are about right for centre line removal. I could imagine this happening on King Street in Kitchener, where the traffic already swings to the right in the face of approaching traffic.
Lots of interesting ideas on the One Street website. Check out this page on street design and share it with your planner friends.