A close reading of the rule cited says, "two vehicles in the park ." That suggests to me that the second vehicle can be in the park, but not at the campsite. When they talk about "other than the designated camping equipment," I think they see this as a tent as the "camping equipment", and a car or van to get you there. So, the second vehicle "must be parked in one of the designated areas provided.) (ie. a parking lot not designated for camping?)"
So a group with some campers in a tent and more in a campervan would work, but probably not 2 campervans. (IMHO). Last year we did see park rangers cruising by every now and then.
Hoping that h1k3rb is able to participate - details to be determined!