Motorhome H approval or not

N’Evening together, I hope I’m right here with my concern: I don’t have a camper yet, but I want to finally get one. I have a Peugeot J5 from ’89 (as a finished camper) in mind. But then I want to completely renew the interior design and design it according to my ideas. My problem is that the J5 is an old diesel, so far away from Euro6 and co. How do you do it with old diesel brummis? Normal registration and then try to avoid cities or Don’t want to get caught? Would you like to spend most of the time in nature with the camper? Or with H-approval? But then I have to expand the camper in a contemporary way, so I don’t want to install solar or LED etc. So how did you do that, how were your experiences?