We have driven to Corfu with our van many times and used it here for 3 to 4 weeks with no problems. The longest spell we had the van here was 4 months because i could not get the insurance cover for europe for any longer than four months ( it is usually 3 months euro cover the same as a car, but I managed to arrange the extra month for one trip only).
My husband is a plumber so we wanted to keep the van here so at a later date if he wanted to start working he had a van, but unless you are already registered as a business you can not own any commercial vehicle in greece. So we were not allowed to import it.
It is a strange law as many people would have a van for their own use not just work.