Car seat positions

Soooooo I have a small issue. I have an 05 4runner and a 15mo and a baby due in a month. My plan was to put a convertible carseat for the 15mo on the drivers side back seat rear facing and the infant seat in the middle. They will not fit this way.

So my question is is it safer to turn the 15mo forward facing or move the infant seat to the passenger side seat and leave the 15mo rear facing?

Update: contacted a carseat specialist with Childrens hospital and their answer was leave the 15mo rear facing and move the infant seat to the passenger side.

Thanks for your answers and figured I'd give the professional answer for those asking