Brule is a great place: a wonderful entry point, campsites that give long views, paddles along shorelines that open to those hills along its west shoreline, good fishing, and those challenging winds that give wild rides atop of those waves building from the northwest. So, it attracts many people: some paddling thru towards Cherokee, Winchell, Davis. or all those connecting routes in the eastern Boundary Waters.
If one counts the sites in the Cone Lakes and Vernon over 30 campsites exist. It appears that many people hang out in the eastern half of the lake, perhaps because it's easier to hide from winds, easier to fish, or a better mix of land and water. The western half of Brule sometimes frightens our canoes: big waves, little shelter from storms, or long fetches to cross.
The campsites are farther apart so if your paddle finds an occupied camp, the search is a bit threating: distance, weather, a bit of fear of paddling west for nothing. Often it seems paddlers, myself included, grab the earliest camp, then hang onto them for several days, sort of jamming up camps when a little paddle west, even into North or South Temperance, might give satisfaction.
The early fall brings many paddlers to Brule, so finding a camp becomes difficult, surprisingly more difficult than an early July week. In crowded seasons, we camp in the Crescent Lake campground, then use day passes to fish, paddle the distances, or just enjoy the views. Remember, Brule is a great place to kayak, use stand-up paddleboards, or even row, so besides us campers-paddlers, other watercraft are filling the sites.
We've tried to paddle or camp on Brule after ice out or in late October/early November for solitude, "best" camps...but those conditions often don't fit our daily schedules at home.
I'm glad that you found a site, enjoyed the heck out of Brule, and I feel your frustrations of finding a campsite. Hope your next trip finds an easier go.