La Wis Wis in in the National Forest, not the Park. Ohanapecosh is about 8 miles north, within the park. The settings are similar, as both campgrounds straddle the Nisqually River. The elevations are about the same.
The National Forest campgrounds tend to have campsites and loops that are a BIT easier for big rigs to maneuver in. But both are pretty tight. I have seen people force some pretty immense rigs into those campsites, at both locations. But keep in mind that these campgrounds and the sites within them were designed for tent camping. Your big rig is as out of place as an elephant in a dog kennel.