We plan the last flight out in the evening too. I am not sure where you will be staying, but on our last couple of trips some of us did hang out by the pool at POR, while those who didn't want to took the boat to downtown Disney to do some shopping and use snack credits we had left.
At POR there are small lockers by the pool, and a bath house with showers and outlets to plug curling iron in etc. I can't remember if there were hairdryers, but I think I just let my hair dry in the sun and curled it (to be presentable for the trip home). There are pool towels to use by the pool. So, you could just pack a carry on bag with change of clothes and whatever you need, throw purse and whatever in the locker, keep a plastic bag to put wet bathing suits in for trip home and enjoy the pool. Of course, this is assuming the resort you stay at is set up this way too. I believe ASM was set up that way too, but way too many trips back to remember.
It's been a few years since we went, but it might be possible to throw the extra items in your suitcase before using the Magical Express (if using). I think we retrieved our luggage from luggage services and brought it to the bus, but honestly I am having a memory laps here!