I just ordered an RT and I have three kids (one toddler and two twin infants). We are counting on the fact that all three child seats fit across the second row. I too am concerned that if we have to haul anyone else, then my eldest will go into the back. which means that we need to be able to access the back via the 60/40 split seat. As I worked out that the child seats only just fit, I would assume that the 60% portion of the second row would be too small to fit the two seats without any overlap. So I do not think it is going to be an easy fix.
Let me know if you find out anything - I havn't actually seen the vehcile yet (I am overseas) so I don't know what to expect.