Pull the membrane is my advice. Spares are more difficult than Baby backs. Spare membranes tend to tear. BB tend to get the whole membrane in one motion. I use a spoon with a square end handle, think flat blade screw driver shape and paper towels.
Many times I have done 12 cases of whole spares (why 12 cases, because my Ole Hickory can hold 108 racks of St. Louis spares), which included opening the box, cutting open the cryovac, removing the three racks, cutting them down into St. Louis spares and peeling the membrane and throwing the rib ends back in the box all in 90 minutes. Another person would season them front and back just as fast as I could trim them.
Chop the vegetables up the day before. Anything that can be done the day before should be done if possible. I assume you will be tending fire so you will have to allow some time for that as you go about prepping. That is something I do not have to do with the Ole Hickory. I would always cook the beans first and hold them in Cambros. A Cambro full of beans would still be over 160 degrees after 6 hours.
It can be done. To help avoid uh-ohs, write out a timeline of tasks that should be completed as you work towards the finish.
Good luck, I know this ain't your first rodeo.
Robert