No, there is no build-in way to do this. But if you know the size of a particular mesh in world units (lets say a height of 10 units) and the size on screen for a particular camera distance (lets say 5 pixels for camera at -10), then you can calculate the size of any mesh at that distance if you know its height in world units (for example: height=20 units -> screenHeight= (5/10)*20=10). The size is linear even when doing the projection, so if you move to -20, the size would be 5, at -5 it would be 20 etc. By knowing this, it should be easy to calculate the correct distance yourself.