Great ideas here...
I think this is what Ron suggested, but the way I would do it is plan on getting them SMOKED to an internal temp of 170° or so - by midnight. Make that your goal...to hit 170° at the most, by midnight.
Then - plop them into a foil covered roaster (with some liquid in the bottom, of course) and set the oven temp at 225°
When you wake up at 6 am - they will be perfectly done (Ron, please chime in here if you think this is good advice.
I don't use an MES, but I've used the oven for over-nighters kinda like this.)
Then do all of the above advice as far as the coolering, and you will be the king once everyone eats it!
Getting the first 5-6 hours on the smoker will give plenty of flavor, so that no one would even be able to tell that they technically finished in the oven.
Also, that 4 - 5 hour window of time from when you leave the house to when you want to pull - that will be fine. If you are insulated well, it will still be VERY hot after 4 1/2 hours.