Be aware that state parks in Wisconsin have no hookups other than electric, and many of those may not be 30 amp. Also, a large trailer such as the OP has will be limited as to sites it will fit in. That said, Wisconsin has some of the nicest SPs in the country. :)
Another option around Wisconsin Dells is the KOA. They do have big-rig sites; most are in their lower level, which is VERY close to the train, which runs frequently - one drawback. If they have a site that fits you in their upper level, I strongly recommend it. Nice owners who care about the CG and the folks who stay there. Convenient to downtown, the Ducks rides, the boats, and the water parks.
Rocky Arbor is nice but will be noisy toward the back end of the CG, as it backs up right to the interstate.