Is it possible to convert a truss attic into living space?
It is definitely possible. My uncle has had this done in his loft. They had to reinforce the trusses with large pieces of wood, but they were single rather than double cantilever so it was easier.

Perhaps it's worth getting some quotes from professionals or hiring an advisor, as they'll be able to give you an idea of what would be involved and the complexity of the task even if you don't use their services.