Death Valley 1/26-1/30 w/ Campervan

Hello DV visitors. The lady & I are driving from Las Vegas to Red Rock Canyon, Joshua Tree & Death Valley after my conference, we're NYC peeps looking for outdoor adventure. This is our very first campervan trip and first time out to the 3 parks as well so we are very foreign to the campervan logistics. I'm aware there's water and sewage hookups at certain sites but they were all reserved, where would we go otherwise? Visitor center? Any info is greatly appreciated from this NYC n00b.