It should be ok - we did it in reverse in Dec. 2009 (stayed at MCO Hyatt last night of trip). We had early morning flight home and DBF was not going to get up at 4:00 a.m. to catch ME. When I made WL ressie, they asked time of return flight, and I asked if I could take the ME to airport the night before around 8:00 p.m. - it was no problem. Last day at WL, we stowed our bags with concierge, went to park, came back to WL to catch ME. We were tired and ready to go early, and so I called the ME line and they moved us to the next ME at 6:30 p.m. ME even dropped us at airport entrance near the hotel. We just took our bags and walked into the Hyatt. For your arrival, I think you could just ask them to schedule you at a time close to when you want to get up and go in the a.m. If you don't want to pay the Hyatt fee, you probably can just carry your bags yourself to ME check-in (we almost got our own bags from carousel and did that when we landed b/c it was a last-minute trip and we hadn't gotten ME baggage tags before leaving - but then found out if we gave our bag claim check to the CM at the ME check-in podium, they would get our bags). Hope this helps!