I used to do 3+3 (adults) wheels on in the older (B9) regular length, but you needed to take 2 of the 3 seats out the back.
The issue with the newer shape is the floor is flat in the back, so you can’t drop the front wheel into the rear footwell any more, which is a shame.
I don’t think 4+4 is going one wheel off, just cos of the width with 2 seats in the back.
4+4 should go with both wheels off. I used to do it in my old blingo with one seat out. Bikes go upside down across the boot (so the longer part of the bike is at the wider window area, if that makes sense. Wheels go in the space the seat you removed left.
Really though if I was doing that a lot I’d get a bigger van.