After much debating and deliberating, we bought a portable toilet for the van. If we were just using the van for weekend jaunts, then we wouldn't have bothered as it takes up valuable space, beside the fact that you will be going to the toilet in the kitchen/bedroom/dining room.
But we may be faced with situations when we can't use a public or campsite loo, and although we have both wild camped and done our business outside it's not ideal (especially in the middle of the night!)
So we bought a portable loo, along with some eco-friendly biodegradable fluid for it (better for the environment than that chemical stuff). You can empty it at most campsites, or if necessary empty the contents down a toilet.
Not a particularly pleasant topic but I have a feeling I may find using it quite amusing.