I haven’t a clue. However, I will note that Stonehearth uses the Horde3D engine, which is apparently open source software. A quick googling suggests that Horde3D is either working on Oculus Rift support or going to do so.
Also, consider this:
Based on all that, I’d say that there’s probably a good chance you’ll be able to add OR support to Stonehearth, at least in principle.
@sdee / @Ponder / @Tom - anything wrong with what I’ve said here (hopes not 
)?