We add a state if we have done something in the state.
Driving through doesn't count for us. Neither does camping in the state. We have to be RVing, but we have to experience the state somehow; a museum, a park, etc.
I saw someone's last year and he had Hawaii on his. I asked him how he camped in Hawaii and he responded that not all of his visited states were places he had taken his RV. Several of the visited states on his RV were places he had flown to. That didn't make much sense to me. Why put it on the camper if you don't take your camper there?
To each their own.
Happy camping!