I tried it that way on my Traeger a couple years ago. I didn't like it for the same reason I don't foil...tasted more like my mom's pot roast than what it really was. Even though the top was open I didn't get the smoke flavor and boiling in it's own fat/juices didn't help. You might think about putting the pan on a shelf down from the brisket and just let it drip in that.