I have seen some people use a short piece of plank or ply wood to act as a makeshift landing ramp too. I have tried to demonstrate both these ideas in photo C (substituting wooden blocks for bricks in this case, but the light wooden blocks probablty wouldn't be heavy enough to stay put for long). A couple of tacks through the ply into the bottom board would be a good idea too.
(I haven't made enough posts for forum software to let me link your image)
I haven't tested to see if the bees get less lost if the hive is a colour other than white. I'll ask around , it would be interesting to know if a darker colour helps with their landing approach.
I use ply landing boards, each one has a different pattern painted on it. I used left over paint, so nothing fancy. One has a stripe leading up to the entrance, another has four dots on it .. and so on. The landing board stays with the colony.