Wow, that's a big group. Not undoable, but it certainly presents challenges. Some go-to ideas that work for a smaller group might not work for such a large group.
I think one of the big challenges you'll have is food storage - it will take a lot of coolers and ice to keep the cold food cold for such a large group. Keeping that in mind, you may want to tailor your menu to minimize how much needs to be kept on ice. While Hot Dogs, Brats, and Burgers can certainly feed a large group fairly quickly, that may end up being a lot of meat per person. Not to mention transporting buns takes up a lot of space. Another go-to idea for Scouts is foil packet meals. You'd need many campfires burning to pull that off for such a large group.
Here's how I'd approach it. Growing up in a thrifty family, we had to be creative in making the meat stretch to feed 7 (Grandma-Grandpa-Mom-Dad-3 Kids). One great option for a group is pasta. You can do it meatless with just spaghetti sauce and dry pasta, or you can offer a meat sauce and a meatless sauce. The meat in the meat sauce will go a long way - a pound of hamburger can stretch nicely. You can buy giant jars of sauce at most warehouse club stores. The pasta you don't use will keep for your next outing as well. You can cook the pasta in stock pots with strainer baskets - pull out the basket, the past drains and can be served, and the water is still on a boil for the next batch. You can probably do several batches of pasta before you'll need to add more water. You can keep an extra pot on the boil so there is no downtime to wait for water to come up to temp. With 3-5 gallon pots, you'd probaby want to have 3-5 pots going at once. If you can find bigger pots than that you might only need 2-3. For the sauce, I'd brown the meat 1-2 pounds at a time in a skillet, and then drain it and transfer it to a pot of sauce. Don't use aluminum pots for the sauce, it can react with the acid. You could use large steel stock pots or large, well seasoned, cast iron dutch ovens. You can stack the dutch ovens with coals in between to keep the whole stack warm.
Another option would be tacos. I'd go with soft tortilla shells, less space and easier to transport. Maybe have tortilla chips for those who prefer crunchy. You could easily do pulled pork or chicken in dutch ovens as a topping, and ground beef as I explain above, transferring it after browning to a larger pot. Again - this stretches the meat a long way.
As for breakfast - large rectangular griddles are your friend. If you are using Camp Chef stoves (highly recommended for a group this size), you can buy griddles that cover their three burner stoves. On a griddle that size you can whip out burgers, grilled cheese, or pancakes in no time. If you are using smaller Coleman style two burner camp stoves, you can get a griddle to cover both burners but the most you'll probably get is 6-8 pancakes, whereas you can probably do 3x that on the Camp Chef in a batch. If you buy precooked sausages that just need to be heated, you can do those over a campfire with a Coleman broiler basket or similar long handled grilling basket. Serve these in batches - one batch can probably feed a den+family. If you have 2+ stoves you can feed multiple dens at a time. You'll be able to crank out another batch of pancakes every few minutes - but serve them while they are hot - don't try to precook for the whole group. Breakfast burritos is another option if you aren't doing the tacos. I'd precrack the eggs and store them in a tupperware style jug. scramble a batch at a time. Serve with shredded cheese, chopped up sausages, salsa, etc.
As I mentioned before, grilling is another option, but transporting grills for that size of a group could be tricky. Stoves are more versatile and I'd probably design my menu around stoves rather than grilling.
Hopefully this helps and gives you some ideas of the thought process around feeding such a large group. Hopefully you have some parents or leaders who enjoy cooking and will take on that role. I know I'd rather be the chef than the dishwasher - especially with a group that size! ;-)