Camp Schuller is pretty packed in width-wise. I couldn't see well enough to tell about length. LOTS of noisy generators running 24/7.
The traffic is only congested when everyone leaves at night or comes in for the afternoon air show. If you go earlier in the day it's not bad. There are shuttles for the parking lots. Do make a note of where you park, and tie some high-visibility thing to your antenna to mark the car. Even a white grocery bag is helpful in the dark. Take a flashlight or phone with a flashlight app. But DO absolutely stay to the end of the fireworks display. Well worth the traffic!
We stayed a the Breezy Hill RV park, formerly a KOA, in Fond du Lac. Well away from the noise & crowds, but about 20 minutes to Oshkosh. Very quiet nice campground up next to a cornfield, with some well-maintained seasonal sites. But call now for reservations! They do raise their prices some for EAA week.
ETA: There were a couple of nights with heavy rains while we were there. People where having to get their RVs towed out because of the mud. I would avoid Camp Schuller, it did not seem to be a pleasant experience.
Single empty-nester in Middle TN, sometimes with a friend or grandchild on board