At the last split, if you go left the single track dumps out into an old defunct campground known as pine knoll. As long as your self-sustained, you could camp right there, but you didn't hear that from me.
There's an official state campground just west of HH on Lake Margarethe, but you'll have to share it with trailer pullers. If you drive east of town on M-72 out to Burton's Landing, there's a primitive campground on the Au Sable. You'll have to share that one with pretentious, cigar-smoking, 7"brook trout catching, lying, bamboo waving fly fisherMEN. I don't know which is worse.
never underestimate the power of denial