Actually Hogger come to think of it if you're light enough and
CFM'd (no IAEs) you might make it in 20 miles out at FL150.
You'd have to disconnect the AP and pull the speedbrake then
drop your gear at Vle, let the speed reduce and pull the flaps
till you end up with Config 3 hanging out, then stowing the
speedie back and pulling out Conf Full a few secs before the
thresh. Old cav-wotnot might **** himself with the approach
gradient being outside his zone of comfort but you'd probably
make it with a few sharp S-turns.
Of course it'd be a very steep approach with the thrust idle
throughout.
Done it in the sim once, but with IAEs I needed close to 23
miles with S-turns. If your sim is CFM'd it might be worth a
fiddle around if there's any spare time left.