The solution being...
a third pilot in the flight deck with a sextant, an independent GPS unit, hard copies of relevant regulations and instrument approach constructions for every airport that will be used, a thermos of coffee, a couple of marmite sandwhiches, a slide ruler in his white shirt pocket, along with 6 ink pens and 6 pencils, a spare set of eye glasses and a pair of dice to calculate the chance of success for each takeoff, approach and missed approach. 😀