Close to Glacier
We ended up at Doris Creek while searching for a campground that was close to Glacier but not in the park (since we didn't make any reservations). It's a decent campground with nice lake access. The sites seem to be catered more towards RVS and campers than tents (we pitched our tent on a patch of gravel) but the ground was level. Pit toilets are available and each campsite has a picnic table.
Month of VisitJune