We bought RV Specific TP once, they day we purchased our first RV with a toilet. The dealership had a campround that we were spending 2 nights in right after we purchased the RV. We brought a lot of stuff with us, but we were so used to using the park's bathrooms (our pop-up didn't have one) that we didn't think about TP. We bought some RV TP at the dealership. Our salesman told us in the future just use Scott Toilet Paper.
Funny story - a few years ago I met a camper at our seasonal site. It was their first time there with their recently bought new RV. Apparently him and his wife didn't know they could use any TP so off to the RV dealership to buy some. Later that day he comes back and asks me how we like our Greyhawk. I tell him how we felt and he said, I think I just bought one. We went to the dealership to buy some TP and ended up putting a deposit down on a new Motorhome. We pick it up in a few days. Now that was expensive TP. I did tell him that we use Scott TP and that any will do.
I have noticed over the last few years that Scott TP no longer says it is RV safe. At one time it did say it was Septic and RV safe, but now it only says Septic safe.
-Michael