I think you answered your own question hehehe. Naturally dli applicable mag-bounce kung taas ug ceiling.
The most challenging is mixing your flash with the lighting on the event. I have gone to three fashion shows and one thing I notice is that the lighting always changing depending on what the wardrobe being showed like kung sport ang look very vibrant ang colors kung formal gani like gowns low light and controlled spot lighting.
One suggestion bai be there early..it really pays to be early kay para maka scout ka unsa lighting then pwesto ka daan and para maka-balo ka sa imo settings daan.
Suggest M mode f2.8~f4 kung wala gani ka fast lens go for f5.6 and 1/100 then my flash set to M 1/.8 so the TTL will not much help with inconsistent lighting. Then adjust lang nmo ang shutter speed ug flash output.
Good luck bai.. asa man ang venue diay?