JUST personal opinion. NOT based on experience.
1) Do you think it's fair to ASK them to store it for 3 nights? (Just being honest here.)
2) If you do ask them, maybe an appropriate gratuity could ease the "pain" of 3 days storage.
3) Maybe bell services (contracted by Disney) actually has a charge for this already. If no one here knows, I would ask them.
Maybe it is more reasonable to run resources down to minimum throw-away and start over when you return to WDW.