Jake, lots of folks do ribs and butts together, but it could be a little tight in the #2. I'm not a "combo" smoker; I like to let each meat have the spotlight all by themselves! (Especially with meats that cook differently).
You can make up brine anytime and keep it in the fridge. That's actually best, because it's cold when you put the meat in. Don't know if your schedule allows it, but here's a thought:
1) Brine the pork butt tomorrow night, around 10-12 hours is fine.
2) Put the butt on, at 235 box temp, early (like before daylight early) Saturday morning. Not sure how big it is, but you can usually count on around 1.5 hours/lb (sometimes more, but I've only ever done 1 or 2 that took longer than 1.5).
3) As soon as the butt hits 190, double-wrap it in foil and let it rest on the counter (to cool enough to refrigerate).
4) Let the smoker cool for 30 min to an hour, with the door open. You should be able to
carefully remove the wood box and reload for the ribs.
5) Put the ribs in. They should take around 5 hours, so you'd have it all done Saturday night.
Both of these meats reheat very well. If you have a crock pot, you can put the wrapped-in-foil butt in there, Sunday morning, for a few hours. When it's hot, unwrap and pull it in front of your guests! (I use a big disposable aluminum roaster pan for this). The ribs can also be heated in a crock, if you have a second. Just put about 1/4" of apple juice in the bottom, and set the half-racks in there on their sides, for a few hours. Remove and slice!
My plan may be way-off, due to me not really knowing your schedule or timing, but maybe it will help you put
your plan together!
