I've be thinking about adding a shallow (bridging) tile for a while. I've been wondering whether it is worth it. What broke the camels back so to speak was the decision to make the tiles 3m tall. The tiles have gone from 80cm high with a radius of 1m to 3m high and a 3m radius. I wanted to do this because I want the edge tiles to be divisible by 9 and to reduce the number of tiles for the planet for performance.
Anyway this is my unit test map for testing path finding. It is also for testing lighting. As you can see, there is a lighting issue underneath the shallow tile.