You've lost me. How are simulators fragile if you overload them?
In the simulators that I flew, any landing not on a runway results in a crash. And a crash is a sudden stop. It is just not possible to make a rollout or a slide if you will after a landing on terrain. You would have to freeze the sim upon touchdown (on the simulators I know, all CAE).
So a sim has zero survivability during an “off airport landing” (nice eufimism Boeing!), it is indeed more fragile then the aircraft.
Anyway in all the all engine flame out scenarios that we train there is a runway within reach and you should be able to make that if you are a little bit current at descent planning and mental math.. like the Air Transat that landed at the Azores.