We have a toyota Landcruiser. I have had 2 forward facing seats in the boot part and 2 rear facing in the middle seats.. Car seat wise it works well.. We leave the seat on the passenger side up and locked into position and our 2 eldest climb in and out that way..

2 car seats can fit easily across the middle seats but makes getting in and out of the back awkward. with 2 seats in the back there is virtually no room for a 3rd child to sit.. but 1 seat in the boot allows for 2 children or 1 child and adult to sit reasonably comfortable in the boot..

hope that made sense