Replying to Just thinkin.. Flip on flip off?

So it seems these days that in any slope comp or rail jam that a variety of flips are done either onto or off of rails.  Namely the rodeo 4 onto a rail, and the misty/rodeo 4's that are done off of rails by pretty much everyone these days.  My wondering is.. how crazy hard would it be to combine the two?  Correct me if i'm wrong, but I don't believe i've ever seen it done before.  To me it seems though like sooner than later someone will be able to rodeo 4 on, and rodeo/misty 4 off.  Any thoughts as to what kind of rail it would take and who would be the first to do it?