To be honest, sneaking a camera on a ride without permission is just a dumb idea. Just ask, thats all you have to do!
Some park websites now have pages to allow you to book a session to film on-ride footage. I've done it before and it works. You get full permission to film coasters and you get a name tag too so that ride operators know that your allowed.
It's better than being banned from the park and possibly sister parks, including the chance of having your camera taken away and destroyed.
Robb knows best, and he says not to!