you have to try urself, though it is not easy to simulate that at showroom.
we did put two isofix car seat in our car, and found it very difficult to climb through
so it is ok to ask my maid to do climb to the back row but not my parent or friends
that's why we willl get one carseat with both isofix and sealt belt fix, just in case we need to put one at 2rd row and one at 3rd row.