I understand wanting to really vet someone first; but it really does seem kind of excessive how long these interview processes are becoming. It's not as if the author were applying for a Japanese salaryman (read: lifetime) employment position. Why not do a normal interview, bring them on as a contractor, see how it goes, and then make your final decision? It'd be a bit of a risk for the candidate if relocation were involved and remote work wasn't possible, but that would be on them.