Dmtky, because you are doing so many, probably best to vac seal as stated above. I dont generally cook that many at one time.
Since I am generally firing the pit for something else when I am going to reheat brisket, here is how I do it:
Prep and rub the brisket, then cook it to around 160. Wrap in foil and continue to cook until about 200. Start probing it until the probe slides in with no resistance. Will feel like going through warm butter. Then pull the brisket, wrap in a towel and allow to rest for about an hour just as if you were going to slice and serve same day. Unwrap from towel and place in the refrigerator over night.
Next day, unwrap the brisket being careful to collect as much of the "jelly" (collagen) as you can into a bowl. Slice the brisket cold, leaving the pieces just as you sliced it. (I had removed the point on this one to make burnt ends towards the end of the cook),
Place the slices into a pan and spread the jelly across the surface. Fan the pieces to get as much between as possible. Cover pan with foil and put back on the pit at about 220 for around 2 hours. probe the meat, when in the 180 range remove, rest, and serve.
Everyone has a different way, this one works for me. One of the advantages I can see of the vacuum seal though, is that the color would still be pretty brilliant. Sliced this way, the meat does begin to brown a bit when reheated.
Backyard Gator Pit