Getting a demo ride at OSH may not be the best place to get this done. It's a very busy and intense time with customers 10 deep asking tons of questions. Might I suggest requesting a ride in a locally privately owned RV12 in your area by just posting it here on the 12 forum.
Demo rides have been known to cost many many thousands of dollars. It varies, but I have known pilots that spent well over $100,000 as a result of one innocent demo ride. I only bring this up because I was a victim.
Steve