There is the potential at least to get a ride at OSH from Vans, but a couple things you need to be aware of.
1. Demand is very high so you will have to reserve as soon as you arrive and doubtful you will be able to get a ride the same day, if at all. I don't know if they take reservations before you arrive or not.
2. You will be able to get a better ride in your own local area than at OSH. IMHO. The airspace is crowded and Vans will have very limited time to deal with each individual. If you find someone locally to give you a ride you will also have a new link into the RV community.
I will be up there with my RV and would be very willing to give a ride - in other circumstances.... I will be too time restricted and don't want to leave the field and then try to get back in again. When I depart, I won't be returning until next year.
Try posting your location and where you would be willing to travel to for a ride, then take someone out to lunch and pay for their fuel. I have a shirt that even says "Will Fly for Food" and often do that