You need an Adventure Pass to park your car at Chantry Flats, and then it’s a 2.6 mile hike with ~1,000 feet vertical gain to Spruce Grove campground.
There are no reservations, but there are seven campsites and it’s pretty rare that they are full. Of course, the earlier you get there, the better.
I’m looking at doing exactly that in May. The creek is running so there is water (it needs to be filtered or treated) and they have pit toilets, fire rings, and picnic tables.