At the rides I have attended, some camping is in the official
state park/forest campgrounds, and others are in a separate area
(usually a big field with access to the trails).
The only size limit I have seen is a plea to keep the size to
a minimum so that everyone will have ample room to set up pens.
We don't have any annual bridle tag fee. A couple of years ago,
the Dept. of Natural Resources here discussed raising the camping
fees. At this time, they are upgrading horseman's campgrounds to
justify higher fees. I believe most of the campgrounds are still
"primitive" and the overnight fee is $5. The sites with electric
are $8. There is also a $1-$2 fee/horse.
The State Forests continue to have free camping.
There is no fee for day riding at either state parks or forests.
Electrics are normally not allowed in horseman's campgrounds, as
they are equipped with either "tie stalls" or picket lines, but
so far, they allow them for the endurance/competitive rides. I
noticed that Indiana's ride flyers stated that no corrals would
be allowed on state lands this year, I hope that Ohio doesn't
follow suit. I certainly sleep better than with a horse clanking
around on our gooseneck trailer, and I know the horses do!