The outlay vs payback thing is a valid one, but there are some aspects of the decision making which need to be considered:
- Are you planning to keep the van for a long time or is the novelty likely to wear off after 2/3 years?
- Do you love the far superior (IMHO) and wilder campsites that have grass pitches and do not offer EHU?
- Do you have a healthy interest in being self-sufficient (without resorting to a generator)?
Each to their own as always, but rocking up somewhere remote and having everything you need feels good. That's why we went for a washroom in the end, and a solar panel, wind turbine or water wheel is the next on our list :-)