Yup I make it 34.4 kilometres...
At 112800ft the ISA atmospheric pressure is 12.766 lb per square foot. (It is 2116.22 lb per square foot at ISA sea-level).
At this point I believe water goes ice to vapour (or back again) without liquid in between. Anything that goes from solid to vapour without a liquid phase is "sublime". Diagrams look fine.
Now let's suppose M0.77, aspect ratio 8.4, L/D about 20... and 60 tonnes weight.
(Sips a sublime gin and tonic)... It needs 80,000sq ft wing area, a wingspan of 820ft with a Lift/Drag of 19.77 and a speed of 460kts and engines burning 0.65lb fuel per hour for every lb of drag to cut along at 106.2 nautical air miles for every 1000lb of fuel. Assuming I can light the kerosine-air engines that is.
I'll let Sir Richard Branson go there. Now if Captain Claret has a bottle handy...