For 14 burgers I would go 2 zone as Mr. Cue suggests. There's a lot to do with 14 burgers you want the cool side for the cheese to melt. Like you mentioned, burgers are page 1 but honestly 14 burgers is chapter 10. I would go with 350-400, lid closed. If you can remember, I'd close the bottom vent while you're flipping the burgers and adding cheese, just remember to open it back up when you close the lid. The will help with the temps rising as was mentioned by Tarheel. Cheese is quick, for me usually 30 seconds lid closed on the classic but it depends on the cheese. Cheddar is longer than american.
A dry run is a good idea and honestly my biggest challenge when I cook 8 burgers which fills up half the classic is room for the spatula to flip. Yes the burgers shrink which helps but give yourself some extra space and do another batch. Good luck!