Motorhome or truck registration

Hello ! I’m new here in the camper area and have a question to which I find no answer. Would like to buy me a T5 high roof and have already made out a good vehicle, which is approved as a truck, Diesler and permissible total weight are 3000kg I wanted the vehicle to drive, transport and use as “Womo light” for vacations. Just how do I register this thing ? As a camper or truck ? What I have to do to get the as WoMo taken away is known to me. My Fr Agen are just those: If I transport things and have the WoMo expansion outside, the thing but as WoMo is approved can make me TÜV/Police trouble ? Conversely: If it is approved as a truck and I have the WoMo equipment in it can cause me the police or TÜV then also trouble ? Taxes are close together: WoMo 210€ and truck 172€, so if they want to seal me then tax evasion would be a sticker amount. Who can help me how I best register the Fzg ? Registering as a car is not possible because then it is twice as expensive and because it is definitely not used like this.