We had been to this area three years earlier, and stayed at Mauthe lake. That suited us better because it is motorboat free, and we have a canoe. Long lake is more suited for powerboats. the sites are also large and would handle big rigs. There are six different campground loops, none near the lake (though the 700 loop has a trail to the boat launch). We stayed in the lower 900 loop, the smallest. Our site, 906, was about 30 feet from site 730. all the sites in this loop are large and deep with the exceptions of 908,910, 912 which are right up against the road and have no privacy. sites 713 & 705 run into each other and are the best for a large group and a pull-through if you get them together.
Pit toilets only. Fire rings are decent. Wood is available 24/7 through a huge "vending machine" that costs $6 (a five and a one, no change) Wood from the shed costs a dollar less, but only when the ranger is at the front gate.
There's a beach with a concession stand and a separate boat ramp with parking.
We went canoeing at the very small nearby Silver lake and had it all to ourselves.
Sad news is that the Parkside general store, with it's ice cream and home-made maple candies is out of business. Zahn's trading post is temporarily closed, and the Woodland Creek Supper club (both in New Prospect) was undergoing renovation when we were there, a shame as we loved it last time.