KISS:
Captain's discretion (means if it works you're a hero; if it doesn't you're a .....) manitain landing flaps if you think you can maintain landing performace; if not retract to F15 and acclerate to white bug or +20kts and land. If G/A from land flaps then F15, (assuming > F15 for landing). If G/A after retracting to F15 AND at +20kts then F1.
I'm not sure where it differentiates bewteen F30 & F40. For me it was LAND flaps.
If at F15 due SE, and the other one fails then retract to what you like and crash ahead, in a controller manner of course, and receive your medal later.
This thread is very relevant considering what happend at CIA where they attempted to G/A with naff all thrust. Brilliant captaincy to stuff it on the ground and all walk away. And No the pilot was not Sully, and No there are no You Tube videos, and I am ashamed to admit I do not know his name, but it should be up there is lights.