We have used the same plan for RSR on our last two trips (including this last weekend) and it's worked perfectly.
We get to the park early (7:15 for an 8:00 rope drop) and make sure we're at the front of the pack with me on the far left and my wife/kids on the far right. When the rope drops, I head for the FP while her and the kids get in line for the ride where I join them as soon as I have the FP's. We ride once, then spend an hour or so in Carsland until our FP window opens. We then grab more FP's (by then the FP return is early afternoon) and head back for the ride to use our first FP's. Later in the day, we use the second set of FP's for a third ride.
That allows us three rides (actually four on this last trip because the ride broke and we ended up sitting for 15 minutes right before you enter Luigi's/Ramone's and they let us ride again) with virtually no wait. It does require you to be at the front of the pack at rope drop though.