I'm not so sure that there will be sufficient parking at OKW for your RV... If I remember correctly, they do not have large open parking lots like they have over at SSR or BC. Like previous posters have said, parking at OKW is right outside your villa.
If it were me, I would park the RV in the overflow lot at Fort Wilderness. You would have to let the front desk know what you were doing so they could print you a pass to place in the window of the RV. The lot at the Fort is designed for RV's and it would be much more protected there than DTD or one of the park parking lots...
But who knows, they might let you park at OKW across several parking spots..