Do you trim a packer brisket?

thillin, there is a hard chunk of fat along one side of the point, I always trim that off, its different than the fat cap fat and doesn't render. Most of the reading I've done also says to trim the fat cap to between 1/8 and 1/4", this would probably help penetration of rub and smoke, I usually don't bother, instead I try to pick one with a thin fat cap in that general range. Packers are kinda messy (lot of waste to cut off before slicing) but totally worth it. When you bite into one of those juicy slices of flat from under the point you'll know why you bothered! Phil calls that area of the flat the "part that never makes it to the table" , its good to be the cook!

What he said

Ditto. If you foil try to save the juices you find in the foil after you cooler the brisket. It's great to use as a base for a sauce for Q, or even steaks you do in the future.