greenman2, do I understand you correctly, you're staying off property so you'll be arriving at AK via car? If that's the case you are better of driving from AK to Epcot. AK closes early (I'm not sure of when you're there but it's usually around 5 pm). If you are planning to go back to AK, you don't have a problem, except that you are going to be adding another 30 minutes back on just to get to your car. If you don't get back until well after AK closing, they will still take you out there on a bus, but the parking lot trams will no longer be running. This happened to friends of mine and that parking lot is HUGE. If you have a car, there is no advantage to leaving it at AK and travelling via Disney transport to Epcot and back, unless you're coming back to AK to do more activities and just going to Epcot for a couple of hours.
Another thought, and fellow DISers, correct me if I'm wrong, but I think you can park in the morning at Epcot and then take a bus to AK. Then in the afternoon when you hopped over to Epcot, your car would already be there.