Having hacked up and reconstructed the inside of the roof to give more head clearance, I got the chance to understand how Lotus originally made the roof, and it's quite clear it was done in 3 pieces. There was an inner skin and an outer skin, and then the scoop was bonded on separately and moulded in before painting. I even uncovered the filler when I sanded away the corners of the scoop to build that lip. The whole thing is very thick and very heavy, and I've gotta say I'm not very impressed with it for what is an OEM piece. 

So do you think that doing it along the back edge will allow me to release the part? I was still a bit worried that the undercut at the front would lock me in enough to not allow release, even if I didn't have that rolled edge at the back. Shouldn't be an issue? 

 I would prefer to do it in one piece if I can because Im doing infusion, and split moulds can be a pain when it comes to sealing properly. I normally envelope bag the whole thing, but on such a large panel that obviously raises the cost of the consumables. Where do you think would be the best place to make the split line, if I needed to do it that way?