Have to agree....not sure why you don't just pay to park at Epcot and then drive to AK when needed..you pay to park just once a day. Just hold onto your parking receipt from the first park.
If there is some reason you need to park at an Epcot resort, I would go for valet parking at BC. It's closer to the International Gateway entrance into Epcot, and you can just head to AK from either Epcot or BC, returning to BC to get your car from AK.
But truly? I would pay to park at Epcot, then drive to AK.