the other problem with flash is that you have to have manual exposure which is currently not a wifibooth feature. and even if it was, you would have to set the exposure to be fairly dark, because the iapd doesn't know the flash is going to fire. this means a dark live view (drawback) with good lighting only when the flash fires (benefit)
godox recently released an ios compatable flash, but I think it only works with their iPhone app
same thing with this company
http://www.tricflash.com/
and there is another company called lume cube I think.
good luck.