I have been trying a maneuver like this myself for some time, but with a twist:

Pull into a wall, then a high stationary hover. Then, perform a 360 waterfall and just when the plane completes one rotation, chop the throttle to fall into a long tailslide.

I call it the "Question Mark" and IMHO it is the hardest non-rolling 3D move I know (needs ultra precise throttle/elevator timing). I have only done it 2 out of 50 times, I think both by pure luck. The trick is a short throttle burst with up elevator right before straightening the plane at 360 degrees in order to re-stabilise it momentarily before it drops through its exhaust plume into the tail slide.

The first time I did it many people happened to watch the flight and were astonished.

Hell, I even watched myself in astonishment, so much as to let the plane slide tail down to a really hairy alititude (hasty shaky inverted recovery at 20 feet and a load of crap down my trousers...). I had only intended to do a single hover-into-waterfall-into-hover but missed the throttle timing at the bottom, resulting in a super tailslide.

Anyone out there good enough to catch this on video???