Well, I did find out the Pinocchio lot is the lot that RV's park in for the day. It is right next door to the Mickey and Friends structure but you enter it from the opposite side. There are signs that direct you. There are trams that run from there (shared with the M & Friends structure) to the front entrance or you can walk too.
Okay if it is not day use then I would talk to the hotel directly - they all 3 use a self park area but I couldnt see any RV spots there. I am sure they probably have them but not obvious. The normal resort fee that you pay includes the parking in the self parking structure (GC also has valet for an additional fee but I doubt that accomodates RV's LOL!) anyway I would talk to the hotel to get specific directions on parking and if you have to pay anything additional. Nothing worse than showing up with your RV and not knowing where to go and where to park! Good luck!!