Well, you said 'fastest way' not cheapest way. If I had known you had 11 going, my answer may have been different. Two van cabs will still be fastest, but certainly not inexpensive.
Depending on the timing of the ADR, using Disney transportation will be the method of choice. Leave at least an hour to get from your POR to YC/BC....75 mins would be even better. You could have a wait of 20 or so mins for the DHS bus to come..then 10 mins on the bus, then a 15-20 min walk to YC/BC..or if the boats are running...up to 20 min wait for the boat to come, 5 mins or so to board, 15+ mins to YC/BC. And you are supposed to be at the restaurant podium about 10-15 mins early.
You could possibly make it in 35-40 mins, but everything would have to line up just right.