Seat modification - Sprinter 2006

Hello there,

Would really appreciate some help and advice from those in the know! I am converting a sprinter to a campervan but my layout design is slightly unique in that I would like a central single seat rather than a single LH passenger seat and single RH drivers seat. 

I have attached pics of the modification I did to a double passenger seat, this was deemed unsafe at MOT as I had removed structural integrity from the base by cutting it in half. Naïvely I thought that there were enough connections to the van floor left for this to be okay.

The issue is complicated by needing a seatbelt in the middle position, obviously the double passenger base as the seat belt stalk built in to it - so my question is:-

Would this be more likely to pass MOT if rather than cutting the base down, I simply cut the back off the LH passenger seat on a double seat base (rendering the LH seat unusable) but allowing a clamber through to the back via the LH passenger seat position?

This would leave the full base intact and seat belt stalk intact?

The only other solution I can think of is to modify a single seat base so the bolt holes lined up with bolt holes in the middle of the van and attach a seat from a convertible car with an inbuilt seat belt, but this sounds much more DIY.

Any advice appreciated,

Josh