The reason that the Jules Verne starts and finishes where it does is that it gives a course length of 21,600 miles - which is the circumference of the planet
An escape hatch doesn't have to be a fitted/ independent item or have any perspex. Cut a hatch hole out of the hull and use that as the hatch with a flag fitted to the indie of the hull. This also get over not have enough flat surface where you want it to fit a manufactured hatch
Looks like 0-90 in the picture.
could try 2 layers of thinner fabric
if you do fillets along the edge, put the glass straight on before the filler cures, saves rubbing down/prep and it will stick like s..t