If they are going in a campervan it will be made from one van so you see loads of these small vans converted from vw transporters for example or a Ford Transit. You are right with Motorhomes the chassis is a van chassis usually fiat, Peugeot, ford ours is Mercedes’ then the body is made by the MH manufacturer and fitted out so ours is Carthago as an examplethe actual cab bit is probably a transit, then the motorhome bit is made by someone else and they are that thick they think it is an actual transit van my parents have a motorhome and the cab is fiat and the actual living quarters are made by another company. I don’t know if any of that makes sense haha I’m not a motorhome expert tbh just know bits and pieces from what my dad tells me