How easy do you think it is to just drop the rudder in conditions like that.
Maybe they could have used ropes to stabilize the rudder, but just dropping it..
I expect it would be slightly harder than postulating from my armchair, that's for sure.
I was imagining cutting the shaft. I've done that with a 1.5" stainless prop shaft and it isn't easy. You'd also be using 110V tools in close quarters with lots of water. Or finding a lot of motivation while using a hack saw...
I think I like your rope to stabilize the rudder idea better.
Depends on the boat though. My formosa didn't have much rudder stock above the bearing, so there wouldn't be enough leverage to do anything useful.
As for the gas powered pumps, as a recovering wooden boat owner, I've eyeballed those for years. True, it is completely independent of other systems, but I don't like the reliability issues of a small gas engine, with varnished up gas, being stored in a salty bilge, firing up when you really need it. Heck, I have enough of a hard time starting my mower after a winter...
The electric ones have less parts to go wrong, though you are dependent on your generator (if you have one) or inverter. My new boat has both, so there is some redundancy there... I wouldn't worry about power inefficiencies though as I expect you'll be running a generator or engine while all this is happening. They make the electric ones pretty big too. Many hundreds of GPM with 2" outlets.
The gas one, if maintained and tested regularly, is a better option, but it also involves another item to scrupulously maintain and test. It involves storing and rotating gas (which I have avoided so far) and is bigger and heavier. Tradeoffs. I like the middle of the road solution of the 110V pump for my boat, but if I were still on a wooden boat (shudder) I would have the gas powered pump for sure.