Bobber with 2 seats - possible?

[sct73]

I have just bought my first GZ250 and want to strip it down to a bobber, however I need to find out the exact laws here in Lanzarote about what is going to be legal.
The other thing I want to do is have it so that it isn't a single seater. Does any one have any suggestions/images etc. I saw online about a temporary pillion seat that Sticks to the rear Fender with rubber sucker lol!!! Not sure if I'd trust that though

[alantf]

I'm in Tenerife. If it's not on the ficha tecnica it won't pass the ITV, so check that out. The Guardia Civil Trafico will probably have all the answers, so check it out with them also.