Peninsula is a great park, you will need reservations though. If you are persistant and check multiple times a day you can pick up a cancelation (tennison bay or weborg point will work) Wagon wheel is also nice I heard but never been there. Along the way you have 3 state parks to choose from. Harrington beach is big rig friendly, Kholer Andre is nicer but a little tight and Point Beach has something like nine miles of shore line and has some sites that would fit you on the back side. If going through the minacqua area check out firefly Or crystal lake. They might be a bit tight though. We camped at all of them multiple times at different sites and we pull a 34 foot travel trailer ( bumper to hitch) and have had no problems except with crystal and firefly which were a little tight but doable.
