Most of these issues I don't see much of a problem with... Regards 50/100 hour checks and the like, bear in mind this normally takes into consideration many takeoffs/landings, maneuvers, stresses etc etc that flying straight and level for 1,500 hours with the odd left/right turn and flap extensions wouldn't induce to such a high degree.
Plus, you could check the spark plugs/main spar and all the other nice things for cracks and corrosion every single day, and the day after the thing fails for no immediately apparent reason. Conversely you could fly for years without checking and it 'might' be fine...
All this is just nitpicking, so my apologies for that, but what DOES concern me about this flight isn't the refuelling, or the poor sleep, or the monotony and spending every single day for two months in close proximity with another person, but the fact that an engine doesn't run off nothing...
... How are they going to feed oil into the engine? How was this accomplished before?
Good luck to them, I think it's a fantastic idea, just so long as they've got their heads screwed on and don't balls it up!