Prolate spheroid Igloo mold gore calculation

I want to have a prototype mold for building igloos. We will build these, shoot some snow on it and remove the mold from inside! I will buy 6 4*8 plastic corrugated sheets. So the circumference at the base will be 24. The problem is that I don't want a perfect dome, I want a prolate spheroid dome. The structure will be much stronger this way. Ration diameter to height should be 5 to 6, or any suggestion you might have to make the best use of the material. I want to have the pattern to cut. With height points and width. Something like this (Those are for sphere...not prolate spheroid) [login to view URL] Or this [login to view URL] Also, I need an entrance so a 3 feet high curved like an igloo entrance with an extra sheet. So I need to know where to cut for that entrance. Thanks!