Single Block Feature Help

Basically im making a mod that includes dead skeletons that are meant as decoration and can drop some simple stuff when brocken but have no idea how to make them generate in random places on the surface and underground. They should be placed one block per generation batch and in walkable places (i.e. not underground airpockets) which makes the block generation and feature placement unusuable for this situation. If anyone has a solution for this i'd very much appreciate it.