Yeah I hear ya now. Based on this new info just go with your original plan. Once you see how long they take in your MES30 set up, you can tweak your plan for next time with more confidence because you'll have experience.
If you put them in at midnight tonight, they'll probably finish around 9 or 10 am. You can rest them in a cooler that is well insulated with old towels for up to 3 or 4 hours, then pull the meat apart, but you'd still ahve a few hours til dinner, so I don't know what to tell you to do then? (Refrigerate then reheat? Oven on "warm"? Those both work, but the choice is yours)
I have a 7 quart crock pot and many times I rest the butt in a cooler like normal, then I pull the meat apart right inside the crock pot, stir in about a quarter cup of bbq sauce for moisture, then set it on "warm" until the party starts. If you have a crock pot that size or bigger, I would recommend that method because it's solves your time problem and clean up is always a breeze b/c there's never any left.....
I'm 90% certain I've gotten two buts to fit before, but it's been a few months. If not, I would just top off the crock pot and throw the rest in tupperware to the fridge. Maybe you get to it later that night...maybe you dont? Either way it's properly stored.
LMK how it turns out!