Chad,
I agree with your idea of doing a large wc before you go. You're only gone 2 days longer than normal between wc so I wouldn't think that that would be a problem. If you have a spare auto feeder I would put 2 of them on the tank and feed 2-3 times daily. That's still less than usual and your water parameters are ok after a week on heavier feedings. Besides with 2 auto feeders you wont run out of grub.
Chris