There is no way, now i can configure additional GA Thrust. Can I?
You don't
need the APU. The checklist starts with "When below 10,000 feet", hence, if you don't set the APU bleed switch to ON (because you still have a fire switch illuminated), you will continue the points in the list and do an unpressurized landing.
In the unlikely event that your go-around procedure will have you climb back over 10.000 feet you would have to reconfigure again. I guess that would be an extremely rare combination and as most said, you would probably do your best to land with an unextinguishable fire.
About when additional go-around thrust is
needed. Need is for me = "won't survive without". Otherwise it is just "nice to have". If you need it or not would depend on your performance calculations. At my company we calculate, in general, with the standard missed approach as our engine out missed approach too. If the calculations showed a need for no bleeds, additional go-around thrust is required. If we can't meet the standard standard missed approach gradient with one engine inoperative, we use an engine failure procedure, that comes from the same database as our takeoff calculations, in those cases additional go-around thrust would almost never be needed, because we would have considerable more height at the departure end of runway. But it could be cross checked with the take-off performance if in doubt or the missed approach altitude is very high.
"Above max landing weight" seems quite arbitrary. Why would I
need additional go-around thrust, even if doing a return at almost max takeoff weight in, say, Amsterdam (flat like a pancake, for our friends overseas). It would maybe be
nice to have, because you could get off work earlier, since a go around wouldn't take that long to accomplish.
But in that case shouldn't it be left a commanders discretion?