How did you put the sextant through the fuselage without a slow depressurisation?
IIRC, the sextant looked something like a professional camera with a long lense sticking out of it there were no quadrants, or external bits and pieces like on a marine sextant. Think submarine periscopes. It was compact self contained unit. The 2" diameter 'lense/periscope was slid up a tube in the flight deck roof, to the 'hatch'. The lever opening the 2" hatch was pulled and with a hiss, the sextant slid up until until the viewer was clear of the fuselage and various seals made to make it airtight and hiss free. On the way out, the lever was pulled which released the sextant enough to be pulled down past the hatch, which could then be closed by the lever and sealed. The sextant was then lifted down and stowed. A lot simpler to do than this description implies.