Can a Multivan rear seat fit in the back of a Lwb T4? Im pretty sure it will. Just that there will a gap by the tailgate, when the bed is folded out.
Yes it will. As you said there will be a 40 cm gap at the rear of the bed though.
I'm sure you could fettle it to mount right at the rear, but then the seatbelts would be 40cm further forward than they are designed to be.
I thought of doing a LWB with Multivan seats, and having a rear facing kitchen that stood on the floor at the back and was higher than the bed section.
Creating a kind of rear bulkhead/headboard type thing.