Well, still very strange - I cannot envisage anyone trying a 5 sector 9:30 CHARTER sequence into an 11hr FDP!
However, to answer your 'question' - basically
1) Any Pilots' Union if they choose
2) The regulator where it can be PROVEN that the flight will actually unavoidably run into discretion - that is against EU regs.
3) The crews by phoning HOTAC and saying 'Where's the hotel'?
Again, it all depends on the 'turn-round' which you have not specified. Yoiu could plan 20mins there for each. I have fuel tech-stopped a 737 out of Banjul in Faro and been off chox in less than 15mins, but it cannot be a regular event.
Firstly it was FARO who have always been excellent.
Secondly it was 'nil change of load' other than fuel for the load sheet
Thirdly we had everything 'ready' on the 3 hour+ sector into FAO. It was literally 'plug and go' - presumably implausible for your scenario.