2nd row seats extra legroom

I know this topic has been covered before, but can't find a recent thread on it. Basically I'm looking at going back to a 110 after giving it up for a more sensible family car (Disco 3). The issue is that the back seats don't have the room for child seats, or as they get older the legroom, especially as I have to use a seat extender being 6'4".

Is it possible to fit 2 front seats in the rear? My idea being to move them in between the wheel arches and move them back slightly rather than cutting into the wheel arches. I have read of people using seat boxes to mount them too but my issue would be where to mount seatbelts. If its a stupid idea let me know it will help in my decision making. TIA

The seatbelts are the main issue, they would be too far forward of course.
I did look at this myself as both my kids are tall, 5'10" daughter and 6'1" son. I'm also 6"1'.
I think an internal roll bar with the added belt mounts is the only option OR two type mini bus seats with built in belts and chassis plates through the floor for a secure mounting.
In the end I just ignored the whining and they gave up.