I will admit to poaching "closed for the season" campgrounds on my bike.....

If I roll up to a primitive DNR campsite, that has the outhouses locked and the pump handle removed for the season, I might very well not pay the pipe. This may be bad form, but I feel justified being a fee scoflaw in this case and simply camping on public lands.

Previously developed campsites are favored over camping on undisturbed terrain under 'Leave no trace' low impact protocols. I think this legitimizes the use of a closed for the season campsite by bicyclists. IMO.

Abandonded, left to fallow state campgrounds are a different beast. SO neat to find out there, and a good map can lead you to them!

and have never run into an issue.