I don't see any Vehicles in the set yet. They are subtypes I assume?

Without seeing the vehicles, I'll say this: I'm a big proponent of finding ways to make things work with existing gameplay mechanics first. If vehicles were equipment, you could easily attach them to their pilots.

If you’re trying to do the reverse… it’s going to get ugly. You’d have to have it lose being a creature and gain being an Aura, Equipment or Fortification.