No foil just means more spritz
Nope, leave the cooker closed, don't touch the meat, it turns out great. Spritz doesn't help a thing when it comes to moisture, except extend cook times, opening the door for a dry result. Get 'em in and out in 4 hours, no issues.
Sure, you could open up cooker every 20 minutes to spritz and it WILL take more than 6 hours to get 'em done. May as well foil 'em if you're gonna do that.