make ghasts rideable while in minecarts

Happy Ghasts are great! I love them. 

They are slow. 

It is ok, because if you need to transport your ghast long distances, you can just put them into a minecart! Then they transport at minecart speed! Hooray! 

But, if you try to get onto the ghast while it is cruising the minecart, it will freeze position as normal, and then pop out of the minecart. I would like it if you could simply RIDE the ghast while it is on the minecart! Then, once there, just run across an activator rail to dismount the ghast from the minecart, and fly away! 

This would mean that it would be easy to follow the ghast also, because if you get out of sight they won't continue their trip!