Three car seats?!

Any advice on how to situate 3 car seats? I have a good size SUV with a third row. So I imagined moving my oldest (will be 5) to the third row. But will she be able to buckle herself in by herself? Currently we still help. Or do I put both the 3 and 5 year olds in the third row so I can leave a seat down in the middle row. That would allow me to get to the back to help with buckles. Any experiences mamas of 3 have advice? They’ll all be 5 and under.