Campervans are extremely expensive for what they are, which is generally old delivery vans long past the life they were built to last. The most sense is in Mazda Bongos, Ford Fredas, Nissan Largos, etc, that were originally built as MPVs, not as vans. The diesel engines in these are old generation with no diesel particulate filters and mostly pre-date dual mass flywheels too, so none of the modern gubbins to worry about. And in fact a diesel without all this stuff is better for short runs from cold because the fuel itself has some lubricity. You can't keep one within the London Emissions Zone, though.