Yes, I did the experiment. And after about 15 seconds I did start to feel the effects, started breathing harder, increased heartbeat, etc. After 30 seconds I felt slightly light-headed, after a minute I had to quit because I was getting a headache. To be honest, that didn't prove much to me. My duration is only three seconds... and right afterward, the train hits 4.5 g's at the bottom of the pullout, so all the blood that raced to the head would go right back. So, if I reduced the duration to 2 seconds or so, would that make it feasible in your opinion?
Lots of coasters hang people upside-down, after all. Screamin Squirrel, Viper @ SFGA, Manhattan Express, the Ring of Fire at the fair... and what about Chaos at Cedar Point? That has some nasty negative g's...
By the way, yes I know the castle "theme" has been done before, but this one I believe will reinvent it. My aim is to really make it feel like riding a mouse as it darts around a castle. So there will be random vertical drops through the floor, outside banking, fast turns through cracks in the wall, etc. And there will be different "scenes", such as a cathedral and a dungeon. This ride is a combination of two ideas... one idea was to build a really original coaster with lots of original elements, the other was to build an intricate 3ds castle as preparation for rendering the city of Catia from my novel "The Second World" Add that on to the crazy inverted elements I've mentioned already, and I think that entitles me to a claim at being an original coaster.