In the smoker
Watch your heat. 235 is where I cook mine at. Brisket WILL stall. I aim for a 201-203 temp after about 16 hours. I do 15-17lb briskets. Remember its about an hour to hour and a half per pound or so. I would say just monitor your heat input, leave the door shut, dont peek, sit back and have a beer!
Wrapped with foil and towels into a cooler, You will be good for a several hours. Before you wrap it in foil give it a little sprits of what your using, the meat will suck the moisture back up while resting.
If you put some towels below and above it, it should last for a number of hours. Remember food safety, you want the IT to remain above 150. Most likely you are good for at least 2 hours and possibly more. It's a good idea to keep a wired therm in it so you can monitor the IT from outside the cooler.
Or you can put it in a 170 degree oven & it will stay hot indefinitely.
Just be sure to add some liquid to the pan & use double wrap foil over the pan.
I use those throwaway aluminum pans, if your catching the juices in a pan below the brisket, just use that.
190 is probably the lowest temp I would pull. It only gets better between 190 and 205, just poke it with the skewer until it slides in with no resistance anywhere, like warm butter! Your brisket looks fantastic!