No mop, if you feel the need, spritz with just a quick shot and the door slightly cracked. Being a RF, your pit will recover heat from the door being open pretty quick, but mopping is overrated, very little of the flavor penetrates the meats surface and it really does nothing for internal moisture, mopping can help build an awesome bark though. It's just like anything else in smoking or cooking, you have to cook to your personal preferences, if you like it, then do it. If you want to mop, then mop, but it will extend out your cook time. As far as pulling the flat at 185, you can, and it will be good, but I can guarantee you if you want melt in the mouth, tender brisket, you need to cook it to toothpick tender, whether that be at 185 IT or 205 IT. You can separate at 185 if you choose or you can wait until the flat is done, I separate after the flat is done, then cube up the point, some au jus from the brisket, some Q sauce and back in the smoker or oven for a couple of hours more.
Good luck with your smoke.
Jeff