Camper Vans are usually too small to contain a dedicated toilet but you can use a portable cassette toilet in the camper van if you need a toilet in the camper van.
So while camper vans are usually not fitted with a permanently installed toilet they can have a cassette toilet installed in them.
Or you can just carry a portable cassette toilet for the camper van and then sit it outside or inside the camper van when you need a toilet.
Personally if I were out in the woods though with the camper van I would sit the cassette toilet outside and use it outside such as in a tent to keep the smell out of the small camper van.