Stefan... have you ever considered moving to a cooler climate?
https://www.kiwistaroptics.com/careers
Incidentally... you might enjoy some of the designs, here:
http://www.cloudynights.com/topic/48...ew-astrograph/
I like the idea of the prescription detailed in post#14 (uses a trepanned C11 primary) 12" clear aperture @ f2.5 and 6 microns in the extreme corners of a 16803 format chip... lots of complimentary radii and only 1 full aperture convex surface. I'd be curious to know what BK7 costs in blanks that size?